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B1. Labyrinths

How to get out of a labyrinth for sure ?

1. Introduction
2. Tarry : in-depth search
3. Tarry : course with overview
4. Tarry : course without overview
5. Tarry : shuttle between two crossroads of the labyrinth
6. Oystein : search by concentric circles
7. Distinction between crossroads and corridor
8. Modeling a labyrinth and shortest path
9. Sources

B1.1. Introduction

Imagine any labyrinth made up of many crossroads and multiple corridors connecting these crossroads. How to get out of this labyrinth for sure ?
Figure 1 above gives an example of a simple labyrinth made up of 7 crossroads (numbered 1 to 7) including a dead end (crossroads 3), 10 corridors and 4 minimal loops ((55), (464), (2452) and (4564)).
The simplest rule for navigating a labyrinth, called the "hand rule", consists of crossing crossroads and corridors, always leaving the same hand (right or left) placed on the wall. This strategy allows you to never get lost in the labyrinth but does not guarantee finding the exit. Either the traveler possibly discovers one of the exits during his journey, or he automatically returns to his start crossroads.
Thus, on the example of Figure 1, with the right hand rule, a visitor lost at crossroads 5 will go indefinitely in circles in the loop (5245) by entering the corridor (52), and in the loop (5465) by entering the corridor (54).
The "rule of the hand" therefore only applies if the start crossroads corresponds to the entrance to the labyrinth, in which case the traveler is guaranteed to cross the labyrinth without getting lost along the way.

A general rule exists. It allows the lost traveler to definitely escape from the labyrinth when it has an outcome (entrance or exit) and, otherwise, to visit it completely before finding himself at his start crossroads. Two search strategies exist :
- In-depth search, when the traveler is completely lost in the labyrinth. Two different rules were published : rule of Charles-Pierre Trémaux in 1882 [LUC], and rule of Gaston Tarry in 1895 [TAR][TOU][ROS1] which is more general.
- Search by concentric circles (or breadth search), when the traveler knows that he is not too far from the entrance to the labyrinth (less than 3 or 4 crossroads for example). The rule was published by Oystein Ore in 1959 [OYS][WAL].
These three rules (Trémaux, Tarry and Oystein Ore) applie to any flat labyrinth, that is to say spread out on a relatively flat surface, as well as to any three-dimensional labyrinth that may include stairs and rooms with multiple floors.

We now describe Tarry's rule and Oystein's rule, then supplementing them with some general properties of labyrinths (Distinction between crossroads and corridor, and Modeling a labyrinth and shortest path).

B1.2. Tarry : in-depth search

When the traveler is completely lost in the labyrinth, the General Rule of the French mathematician Gaston Tarry is a double rule which is stated as follows :

B1.3. Tarry : course with overview

In the fun case where the traveler has an overview of the labyrinth, the traveler must analyze each crossroads and its adjoining corridors as follows :
A. Just before entering a crossroads, the traveler must mark the Corridor of first Visit to the crossroads (PV) which is the corridor through which the visitor enters the crossroads for the first time. To do this, he creates a PV mark at the right end of the arrival corridor.
B. Just before leaving the crossroads, the traveler must mark the Last departure corridor from the crossroads (D) which is the most recent corridor through which the visitor exits the crossroads. To do this, he creates a D mark at the right entrance to the departure corridor.

Let's see this course on the example of Figure 1.
The crossroads are marked by the numbers 1, 2... 7 where 1 is the start crossroads of the lost traveler and 7 the only outcome of the labyrinth (entrance and exit). The route of a corridor is noted by the number of the start crossroads followed by the number of the end crossroads, for example (24).
Initially, the traveler finds himself lost at crossroads 1 and seeks to reach the exit of the labyrinth (crossroads 7).

Figure 2 above shows a possible course accompanied by the marks created at the end of each arrival corridor (PV or no mark) and at the entrance to each departure corridor (D).
In the case of a dead end (single-exit crossroads), the PV and D marks are not useful since the traveler will never return to this crossroads (see crossroads 3 in Figure 2).
Let's start from the crossroads (1) and take the only possible corridor (12).
At crossroads 2, choose one of the four unexplored corridors, for example (24). At crossroads 4, let's choose, for example, corridor (45). At crossroads 5, let's choose for example corridor (52). Until now, it has been easy to apply the general rule because there was, at each crossroads visited, an unexplored corridor and each crossroads was visited for the first time.
At crossroads 2 (already visited), we cannot take corridor (21) which is the corridor of first visit to the crossroads (cf rule no. 1), nor corridor (24) already taken in this direction (cf rule no. 2). The only option left is to turn back via the corridor (25).
At crossroads 5 (already visited), let's choose for example the right corridor which is in fact a loop (55). Back at crossroads 5, let's choose for example the corridor (56). At crossroads 6, let's choose for example the corridor (64).
At crossroads 6, let's choose, for example, corridor (64).
At crossroads 4 (already visited), by application of rules no. 1 and 2, we can only take one of the two unexplored corridors (43) or (46), or turn back via the other corridor (46).
The first tactic is called "Crazy Ariadne", the second "Sage Ariadne or Trémaux Algorithm". These two tactics are equivalent if we seek to explore the entire labyrinth. The "Crazy Ariadne" tactic is, however, preferable if we are looking for a way out. Let's choose this tactic and take the corridor (43).
At crossroads 3 (dead end), we must turn back via corridor (34).
At crossroads 4 (already visited), let's choose for example the unexplored corridor (46) then, arriving at crossroads 6, the corridor (67) leading to exit 7.
In total, the course between start 1 and exit 7 of the labyrinth is given by the succession of corridors (12)(24)(45)(52)(25)(55)(56)(64)(43)(34)(46)(67).
The corridors of first visit to each crossroads are indicated in bold font.

B1.4. Tarry : course without overview

In the real case where the traveler does not have an overview of the labyrinth, the traveler must stop at each crossroads and go completely around it in order to analyze all the adjoining corridors as follows :
A. Just before entering a cossroads, the traveler must temporarily mark the arrival corridor as the assumed corridor of First Visit to the crossroads. To do this, it creates a P mark at the right end of the arrival corridor. This mark also allows you to go completely around the crossroads, returning calmly to the P mark.
   - If the assumption is true (crossroads having no PV mark), the traveler must change the P mark to PV mark in order to be able to apply rule no. 1 during a next visit to the crossroads.
   - If the assumption is false (crossroads already having a PV mark), the traveler must cancel the P mark by crossing it out ("P crossed out") in order to return to initial conditions during a next visit to the crossroads.
B. Just before leaving the crossroads, the traveler must mark two particular departure corridors at the right entrance to each corridor. He must first cancel the D mark of the last corridor explored by crossing it out ("D crossed out"). He must then create a D mark on the corridor he is going to take. The "crossed out D" mark is only useful if the traveler plans to commute through the labyrint between an finish crossroads and a start crossroads. Note that, although crossed out, this mark remains a mark of a corridor already explored, therefore eligible for rule no. 2.
Figure 3 above shows the same course as that of Figure 2, accompanied by the marks created at the end of each arrival corridor (P, then PV or P crossed out) and at the entrance to each departure corridor (D crossed out if D exists, then D).
In the case of a dead end (single-exit crossroads), the P, PV and D marks are not useful since the traveler will never return to this crossroads (see crossroads 3 in Figure 3).

In the case where the traveler has nothing to mark the walls of the corridors but where he has small stones (like Tom Thumb), then the marks can be advantageously replaced as follows.
But be careful not to confuse the right entrance and left entrance to each corridor when going around the crossroads !

B1.5. Tarry : shuttle between two crossroads of the labyrinth

If the traveler has made sure to keep only one D mark at each crossroads (see point B above), he can then commute, at any time and without getting lost, between two crossroads of the labyrinth as following :
- Returning to a start crossroads (for example to pick up a person left there waiting) then becomes possible and easy. At each crossroads, simply take the corridor marked PV at the left entrance to the corridor in the opposite direction, without generating new marks [PET]. The return path from an finish crossroads to any start crossroads in fact constitutes a tree whose trunk is this start crossroads and whose branches are the corridors marked PV (see Figure 5 below).
Proof : Any crossroads visited the first time is via a corridor traveled from another crossroads necessarily visited the first time. Consequently, any crossroads visited for the first time is on a tree whose trunk is the start crossroads and whose branches are the corridors of first visit to each crossroads.
This tree is called "tree of corridors of first visit to each crossroads" or "tree of crossroads visited the first time".
- Then returning to the finish crossroads (for example to bring the person back with you and continue the search together) also becomes possible and easy. At each crossroads, simply take the corridor marked D at the right entrance to the corridor in the same direction, without generating new marks [PET]. The return path from a start crossroads to any finish crossroads also constitutes a tree whose trunk is this finish crossroads and whose branches are the corridors marked D (see Figure 6 below).
Proof : Any crossroads visited the last time is via a corridor traveled from another crossroads necessarily visited the last time. Consequently, any crossroads visited last time is on a tree whose trunk is the finish crossroads and whose branches are the last departure corridors from each crossroads.
This tree is called "tree of last departure corridors from each crossroads" or "tree of crossroads visited last time".

B1.6. Oystein : search by concentric circles

When the lost traveler knows that he is not too far from the entrance to the labyrinth (less than 2 or 3 crossroads for example), the general rule of the Norwegian mathematician Oystein Ore allows this entrance to be reached by concentric circles from the start crossroads, without the need to explore the labyrinth in depth.
The general rule is then the following [WAL] :

In the fun case where the traveler has an overview of the labyrinth, the general rule applies without difficulty.
Figure 7 below shows a possible course from the start crossroads of the labyrinth in Figure 1, accompanied by the marks created on each corridor traveled (lines or crosses).
The succession of corridors traveled is as follows. Condemned corridors are indicated in bold font.
- Remote exploration of 1 crossroads : (12)(21)
- Remote exploration of 2 crossroads : (12)(24)(42)(25)(52)(21)
- Remote exploration of 3 crossroads : (12)(24)(45)(54)(46)(64)(46)(64)(43)(34)(42)(25)(55)(56)(65)(52)(21)
- Remote exploration of 4 crossroads : (12)(25)(52)(24)(46)(67)
The exit from the labyrinth (also corresponding to the entrance) is found after exploration by concentric circles at a distance of 4 crossroads.

In the real case where the traveler does not have an overview of the labyrinth, the traveler must stop at each crossroads, take a complete tour in order to analyze all the adjoining corridors, then take the return corridor in possibly condemning him. The traveler can then take the wrong corridor when a crossroads has several exits marked with a single line. For example, for crossroads 5 in step 3 below, when taking the return corridor (54), the traveler may mistakenly take the corridor (52) traveled in step 2.
The general rule must therefore be supplemented as follows :
4 bis - Just before entering a crossroads via a new corridor (unmarked and not condemned), when marking the corridor end with a simple line, the traveler must add a different mark (for example P). This particular mark will allow you to calmly take the complete tour of the crossroads and take the return corridor without mistake.

B1.7. Distinction between crossroads and corridor

A labyrinth described in the form of a graph does not present ambiguity between crossroads and corridors, a crossroads being a node of the graph and a corridor an arc connecting two nodes.
But in reality, a crossroads or a corridor is a navigation area that can be complex to analyze at the topological level : more or less vast, more or less narrow area, with the possible presence of niches, shallow dead ends, protusions or small islets. In a crossroads already visited, the traveler may, for example, not find the exact location of an exit or worse, see new corridors appear within the same crossroads. When traveling (in the opposite direction) through a corridor already traveled, the traveler can also, for example, see new crossroads appear within the same corridor.

To avoid any ambiguity, the vocabulary must be rigorously defined as follows :
- A Labyrinth is a set of Crossroads whose Exits are all connected to Corridors.
- A Crossroads is a Navigation area with 1 Exit, 3 Exits, or more than 3 Exits (see example in Figure 8 below). The "1 Exit" case corresponds to a dead end, which is the end of a blind Corridor (crossroads 3 in Figure 1 above), or any single-corridor crossroads that may be a start crossroads (crossroads 1 in Figure 1) or an outcome from the labyrinth (crossroads 7 in Figure 1).
- A Corridor connects two Crossroads by a single Section or by a succession of several consecutive Sections (see example in Figure 8). A Corridor can form a loop when it connects two Exits from the same Crossroads (case of Figure 8).
- A Section is a Navigation area with exactly 2 Exits (see example in Figure 8). A Section is generally empty (without islets) and narrow. It can also be presented in reduced form in length, such as a doorway between two Crossroads.
- A Navigation area is a connected space (in one piece) as large as possible, having all its points intervisible or quasi-intervisible, and delimited by one or more Exits. The space may include niches, shallow dead ends, protusions and small islets. Figure 8 below gives an example of three Navigation areas : 1. a Crossroads (indicated in bold font) including five Exits (S1, S2, S3, S4, S5), a niche (N), a shallow dead end (C), a protusion (A) and two small islets (I1, I2)) ; 2. an empty Section (S3, S) ; 3. a Section (S, S4) with a small islet ; these two Sections forming a Corridor between the S3 and S4 Exits of the Crossroads.
- An Exit is the limit of a Crossroads or a Section, beyond which the intervisibility criterion for a Navigation Area is no longer respected.

B1.8. Modeling a labyrinth and shortest path :

When we have an overview of a labyrinth, it can be modeled by an incidence matrix (M) whose rows and columns are the crossroads numbers and each element of the matrix indicates the number of corridors (0, 1, 2, etc.) connecting one crossroads to another [WAL]. Figure 10 above shows an example of a labyrinth and its corresponding incidence matrix.
The incidence matrix also makes it possible to model a labyrinth with one-way corridors [WAL] provided that these corridors do not form a loop connecting two exits from the same crossroads or a loop connecting two crossroads.

For study purposes, any labyrinth can be simplified as follows :
1. Any dead end can be removed by considering that it is integrated (as a shallow dead end) into the crossroads leading to it.
2. Any loop connecting two exits from the same crossroads can be removed by considering that it is integrated (as a small islet) into the crossroads.
3. Any loop connecting two crossroads can be reduced to a single corridor between these crossroads by considering that it is integrated (as a small islet) into this corridor.
4. Any crossroads whose number of corridors is reduced to 2 by one or more of the preceding simplifications can be removed by directly connecting the two corridors.
5. Any crossroads with n corridors such that n > 3 can be replaced by a ring formed by n crossroads with 3 corridors each [STE] on condition of agreeing to violate rule no. 2 in the modified crossroads in order to be able to travel the ring between any two crossroads (see Figure 9 above).
If the traveler knows how to navigate the modified labyrinth, then he or she can also find a path through the original labyrinth by restoring the original crossroads and corridors.
Figure 10 shows the labyrinth equivalent to that of Figure 1 by applying simplifications 1 to 4.

The incidence matrix of a labyrinth makes it possible to find the number of corridors of the shortest path connecting one crossroads to another [WAL].
By multiplying the matrix M by itself (see Figure 10), we obtain a new matrix (M²) whose elements indicate the number of different ways of going from one crossroads to another via a path made up of 2 corridors. By repeating the operation n times, we obtain a matrix (Mⁿ) whose elements indicate the number of different ways of going from one crossroads to another by a path made up of n corridors [WAL].
To find the shortest path connecting one crossroads to another, it is then sufficient to raise the matrix M to a power such that the element corresponding to the connection between these two crossroads becomes non-zero. The power then gives the number of corridors of the shortest path [WAL].
Figure 10 above shows that the shortest path to go from crossroads 1 to crossroads 7 is obtained for n = 4 with 2 possible paths made up of n = 4 corridors.

B1.9. Sources relating to labyrinth

[LUC] Edouard Lucas, Le jeu des labyrinthes, in Récréations mathématiques, tome I (2ème édition, Paris, 1882), chapitre 3, pp. 41-55.
[OYS] Oystein Ore, An excursion into labyrinths, in The Mathematics Teacher, pp. 367-370, Vol. 52, N°5, May 1959.
[PET] Régis Petit, Labyrinthes et arbres, article de la revue "CANAL.N7", journal de l'association des ingénieurs de l'I.E.T.- E.N.S.E.E.I.H, N°33 de septembre 1994.
[ROS1] Pierre Rosensthiel, Les mots du labyrinthe, Revue CoEvoluion. N°11. Hiver 1983.
[ROS2] Pierre Rosensthiel, Labyrintologie mathématique, in Mathématiques et sciences humaines, tome 33 (1971), p.5-32.
[STE] Ian Stewart, Algorithmes labyrinthiques, article de la revue Pour la science, rubrique Visions mathématiques, N°162 d'avril 1991.
[TAR] Gaston Tarry, Le problème des labyrinthes, Nouvelles annales de mathématiques 3e série, tome 14 (1895), p. 187-190.
[TOU] Pierre Tougne, Comment explorer un labyrinthe ?, article de la revue Pour la science, rubrique Jeux mathématiques, N°60 d'octobre 1982, réactualisé dans Pierre Tougne, L'exploration d'un labyrinthe, Dossier Pour la science, Avril/Juin 2008.
[WAL] Jearl Walker, Comment traverser un labyrinthe sans se perdre ni tourner en rond, article de la revue Pour la science, rubrique Expériences d'amateur, février 1987.

B2. Benford's law

Benford's law, or Newcomb-Benford law, or law of abnormal numbers, or law of the first significant digit, shows that in everyday life, the first significant digit of numbers is not equiprobable : the number 1 is more frequent than 2, itself more frequent than 3, etc.
This curiosity is observed in many fields such as the human and social sciences, tables of numerical values, genetics, construction, economics (exchange rates) or even in the street numbers in one's address book [WIK1].
Open the page of a newspaper at random, note all the numbers you find there. Then look at the first significant digit of each number. It is the leftmost digit, which is not zero. Do not take into account either the sign or the place of the decimal point : for example, the first significant digit of the numbers 0.038   3.14159 and -32 is 3.
To your great surprise, you will notice that the digit 1 appears for almost a third of the numbers, the digit 2 approximately once in 6, and that the frequency of appearance decreases until the digit 9 (less than once in 20) [ROU].

1. Definition
2. Application areas
3. Explanation
4. Case of the digits following the first
5. Case of the sequence of natural integers
6. Case of numerical sequences
7. Sources

   

B2.1. Definition :
Benford's law gives the theoretical value (f) of the frequency of appearance of the first significant digit (c) of a measurement result expressed in a given base (b) [WIK1] : f_c = log_b(1 + 1/c)
We verify that the sum of the frequencies f_c is worth : ∑_{i = 1, (b-1)} [log_b(1 + 1/i)] = log_b(b) = 1
In the decimal system (base b = 10), the law is therefore : f_c = log₁₀(1 + 1/c)
For example, the Benfordian probability that a base 10 number begins with the digit c = 1 is as follows : f₁ = log₁₀(2) = 30.1 %
The table above gives the frequency f_c in percentage for each value of the first digit c between 1 and 9.
Benford's law remains invariant by changing the number base and also by multiplication by a constant, particularly when changing units.

B2.2. Application areas :
Benford's law applies all the better when the series of numbers is "rich", with numbers of varied origins (case of a good mixture of any series) and/or relatively well spread over a range covering several orders of magnitude (sizes of cities for example) [ROU][DEL2].
Thus, the house numbers found in an address directory satisfy Benford's law quite well [DEL1]. If a street has 50 numbers, then more than a fifth of the numbers start with a 1 (because of 10, 11, 12... 19). If it has 20 or 200, more than half of the numbers start with a 1. It is therefore normal to find on average more often numbers starting with a 1 than with 9 (and more generally with the digit c than with c + 1) [LED1].
Benford's law does not apply for various cases, including the following [WIK1][DEL1] :
- Numbers drawn at random (the digits c will then all be equally probable).
- Numbers whose first digit is imposed, for example telephone numbers or vehicle registration numbers.
- Restricted scale of possible values, for example the height of individuals in meters (almost all measurements starting with the digit 1) or the selling price of a particular model of new car (the price varies little from one dealer to another) to another).

Benford's law is mainly used to detect tax, financial, accounting and scientific fraud. The principle is as follows : if they regularly extend over several orders of magnitude, the numbers appearing in accounts or statistics must, unless there are special reasons, verify Benford's law. If these are invented numbers, then the forger must have wanted to create as many starting with 1 as with 2, 3, etc., which will contradict Benford's law [DEL2].
In a document containing N numbers, if N_c is the number of times the first significant digit is c, if f_c is the frequency of appearance of the digit c according to Benford's law, then we define a test statistic T as follows [AMQ][WIK2] :
T = ∑_{c = 1, 9} [ (N_c - N f_c)² / (N f_c) ] = N ∑_{c = 1, 9} [ ((N_c/N) - f_c)² / f_c ]
For large N, the statistic T then behaves like a variable of the law of X2 at v = (9 - 1) degrees of freedom [AMQ].
By comparing T with the quantile Q of order 95 % of the X² law with v = 8 degrees of freedom [WIK2], we can conclude that the series of numbers is most certainly faked in the case where T > Q

Benford's law is also used to detect the existence of hidden messages in images (steganography). Two main methods exist [ATO] :
The first method examines the lead digit distribution of the raw contents of the bytes of a suspect image.
The second method examines the distribution of lead digits of quantised discrete cosine transform (DCT) coefficients of the JPEG encoding.


B2.3. Explanation :
Benford's law remains imperfectly explained to this day [DEL1]. The best explanation seems to be this :
We demonstrate mathematically that the sequence of natural integers (1, 2, 3... n) satisfies a "weak" form of Benford's law (in the sense of Cesàro's iterated averages) [DEL1].
This is why it seems legitimate, when the data set is "rich" (see Application areas above), to find statistically in everyday life, series of numbers whose first significant digit is not equiprobable and approximately follows Benford's law.

B2.4. Case of the digits following the first :
1. Case of a block of digits in first position [WIK1] : The Benfordian probability that a number in base b begins with the digit block (cde) is as follows : f_cde = log_b(1 + 1/cde)
For example, for the block cde = "314" in base 10, we have : f₃₁₄ = log₁₀(1 + 1/314) = 0.138 %
Another example, for the block cde = "10" in base 3 (i.e. cde = 3 in base 10), we have : f_cde = log₃(1 + 1/3) = 26.2 %
2. Case of a digit in position k [WIK1] : The Benfordian probability that a digit (c) is at a given position (k > 1) in a number in base b is as follows : f_c = ∑_{i = b^k-2, (b^k-1 - 1)} [log_b(1 + 1/(i b + c))]
For example, the Benfordian probability in base 10 that the digit c = 0 appears in the second position (k = 2) is : log₁₀(1 + 1/10) + log₁₀(1 + 1/20) + ... + log₁₀(1 + 1/90) = 12.0 %.
This law quickly approaches a uniform law with a value of 10 % for each of the ten digits (see Table above).

B2.5. Case of the sequence of natural integers :

For the sequence of natural integers (1, 2, 3... n), the digits c in base b are only equally distributed (of frequency M = 1/(b - 1))) when n is exactly (b - 1), (b² - 1)... (b^p - 1) for p integer ≥ 1, which almost never happens [CHA].

Otherwise, the frequencies of the first digit c in base b constantly oscillate between two extreme values M_sup and M_inf taken respectively at n_sup and n_inf, such that [WIK1][CHA] :
n_sup = (c + 1) b^{p - 1} - 1
n_inf = c b^p - 1
M_sup = ( (b^p - 1)/(b - 1) ) / n_sup   which tends to   M_supapp = b/( (c + 1)(b - 1) )   for p = +∞
M_inf = ( (b^p - 1)/(b - 1) ) / n_inf   which tends to   M_infapp = 1/( c (b - 1) )   for p = +∞
We have the relation :   M_inf ≤ M_infapp ≤ M ≤ M_supapp < M_sup   since we always have :   1 ≤ c ≤ b - 1   and   b > 1

In base 10 and for p = 1, the value of the couple (M_sup, M_inf) is :
    (1, 1/9) for the digit 1, obtained in (n_sup, n_inf) = (1, 9),
    (1/5, 1/49) for the digit 5, obtained in (n_sup, n_inf) = (5, 49),
    (1/9, 1/89) for the digit 9, obtained in (n_sup, n_inf) = (9, 89).
In base 10 and for p = 2, the value of the couple (M_sup, M_inf) is :
    (11/19, 11/99) for the digit 1, obtained in (n_sup, n_inf) = (19, 99),
    (11/59, 11/499) for the digit 5, obtained in (n_sup, n_inf) = (59, 499),
    (11/99, 11/899) for the digit 9, obtained in (n_sup, n_inf) = (99, 899).
In base 10 and for p = +∞, the value of the couple (M_supapp, M_infapp) is :
    (5/9, 1/9) for the digit 1,
    (5/27, 1/45) for the digit 5,
    (1/9, 1/81) for the digit 9.
For example, the graph above shows the frequency curve of the first digit 1 (in red) and that of the first digit 9 (in blue) for integers from 1 to 10,000, in logarithmic scale [WIK1].

The sequence f_c(n) therefore does not converge and oscillates indefinitely between two extreme values. To smooth these oscillations [DEL1], we take the average s_c(n) = (1/n) ∑_{k = 1, n} [f_c(k)], called Cesàro average. The new sequence s_c(n) still does not converge but varies in a narrower interval.
By repeating this averaging process (t_c(n) = (1/n) ∑_{k = 1, n} [s_c(k)]), we obtain successive sequences (t_c(n), u_c(n), etc.) which vary in increasingly narrow intervals and B. Flehinger demonstrated in 1966 that the interval that we obtain by continuing these calculations of averages of averages approaches, to infinity, the expected value of the Benford's law, i.e. log_b(1 + 1/c)
Thus, the frequency of integers starting with the digit c satisfies a "weak" form of Benford's law (in the sense of Cesàro's iterated averages), each frequency converging towards the value log_b(1 + 1/c)
This convergence in the Cesàro sense makes it possible to converge sequences which were divergent. Known example, the sequence "01010101..." converges to 1/2 in the Cesàro sense.

B2.6. Case of numerical sequences :
Certain remarkable numerical sequences satisfy Benford's law at infinity, that is to say that the proportion of the terms of the sequence up to n, the first digit of which is c, tends towards the value log₁₀(1 + 1 /c) when n tends to infinity.
This is the case of the sequences 2ⁿ, nⁿ and (n!), as well as the coefficients of Newton's binomial [DEL1].
It is the same for any sequence rⁿ where r is a positive real such that log₁₀(r) is not a rational number (that is to say a ratio of two integers) [DEL1].
It is also the same for any sequence defined by a recurrence relation of type : u(n) = a₁ u(n - 1) + a₂ u(n - 2) + ... + a_p u(n - p), in particular for the Fibonacci sequence (defined by : u(0) = u(1) = 1 and u(n) = u(n - 1) + u(n - 2)) [DEL1].

B2.7. Sources relating to Benford's law

[AMQ] Association Mathématique du Québec, La loi de Newcomb-Benford ou la loi du premier chiffre significatif.
[ATO] P. Andriotis, T. Tryfonas, G. Oikonomou, T. Spyridopoulos, On Two Different Methods for Steganography Detection in JPEG Images with Benford's Law, NATO Spie conference 2013.
[CHA] Jean-Marie Champeau, Les illusions - La loi de Benford.
[DEL1] Jean-Paul Delahaye, L'étonnante loi de Benford, article de la revue Pour la science, rubrique Logique et calcul, N°351 de janvier 2007.
[DEL2] Jean-Paul Delahaye, Une explication pour la loi de Benford, article de la revue Pour la science, rubrique Logique et calcul, N°489 de juillet 2018.
[ROU] Thierry de la Rue, Gaëlle Chagny, L'incroyable statistique des premiers chiffres, Université de Rouen.
[WIK1] Wikipedia, Loi de Benford.
[WIK2] Wikipedia, Test du X².

B3. Crossword puzzles

Listed below are the largest crossword puzzles designed without any black squares ("perfect" crossword puzzles)), known in French, English, Italian, Spanish, Latin, Serbian, Croatian,Hungarian, Hebrew.
Some crossword puzzles are classic (with different words horizontally and vertically), others are symmetrical (called "word squares" or "magic letter squares").
In both cases, the most "beautiful" crossword puzzles are those for which all words are expressed in the same language and each in the form of a single common noun, that is to say different from a proper noun and without any separator such as a space, period, hyphen or apostrophe. They are indicated by the label ***

The records for the largest perfect crossword puzzles in 2024 are as follows :
1. In French :
     *** Jean-Charles Meyrignac (classic 9x8 crossword puzzle)
     * Claude Coutanceau (classic 9x9 crossword puzzle)
     * Michel Laclos (symmetrical 10x10 crossword puzzle)
2. In English :
     * Jeff Grant (symmetrical 12x12 crossword puzzle)
     * Jeff Grant (symmetrical 11x11 crossword puzzle)
     * Rex Gooch (2 symmetrical 11x11 crossword puzzles)
     *** Matevz Kovacic (symmetrical 10x10 crossword puzzle)
3. In Italian :
     *** Author unknown (symmetrical 8x8 crossword puzzle)
4. In Spanish :
     *** Author unknown (symmetrical 8x8 crossword puzzle)
5. In Latin :
     *** Eric Tentarelli (2 symmetrical 11x11 crossword puzzles)
6. In Serbian :
     * Boris Nazanski (symmetrical 10x10 crossword puzzle)
     * Zivota Stankovic (symmetrical 10x10 crossword puzzle)
7. In Croatian :
     * Milutin Tepsic (symmetrical 11x11 crossword puzzle)
     * Zarka Dokica (symmetrical 11x11 crossword puzzle)
8. In Hungarian :
     * Author unknown (classic 9x9 crossword puzzle)
9. In Hebrew :
     * Author unknown (classic 10x10 crossword puzzle)
10. In other languages :
Other perfect crossword puzzles are available in otherlanguages (*) but with modest dimensions (8-By-8 and smaller). See [CPT Collection].
(*) Arabic, Armenian, Belarusian, Bulgarian, Chinese, Czech, Danish, Dutch, German, Greek, Hindi, Kazakh, Korean, Lithuanian, Macedonian, Persian (Farsi), Polish, Portuguese, Romanian, Russian, Slovenian, Swedish, Turkish, Ukrainian.

Acknowledgments : The author thanks Jean-Charles Meyrignac for his help and the provision of some of the sources.
Help us : If you know of any other crossword puzzles that are 8x8 or larger, please Contact us.

B3.1. French crossword puzzles :

Classic crossword puzzles (one 9-By-9 and one 9-By-8 crossword puzzles) :

* Figure 1 : 9-By-9 crossword puzzle created in 2010 by Claude Coutanceau [DRI][WIK, Mots croisés].
Horizontally :
  REABRASES : du verbe réabraser (abraser à nouveau)
  ENCRENENT : du verbe encréner (faire des créneaux)
  OCTOCORDE : instrument de musique constitué de 8 cordes à 8 notes conjointes
  CHICORIUM :
         1. Erreur d'orthographe courante pour le nom Cichorium, genre botanique relatif aux chicorées. Cette faute se trouve souvent dans les articles culinaires, voire scientifiques.
         2. Nom d'une entreprise basée à Pulborough en Angleterre.
  RAVAUDERA : du verbe ravauder (raccommoder en couture)
  EPARTIRAS : du verbe épartir (épandre)
  RENIERONS : du verbe renier (désavouer)
  ALTERANTE : de l'adjectif altérant (qui altère)
  SASSASSES : du verbe sasser (tamiser)
Vertically :
  REOCRERAS : du verbe réocrer (ocrer à nouveau)
  ENCHAPELA : du verbe enchapeler (coiffer)
  ACTIVANTS : de l'adjectif activant (qui active)
  BROCARIES :
         1. Ancien écart ou hameau de la commune de Varennes en Dordogne
         2. Du verbe catalan brocar (deuxième personne du singulier du conditionnel) signifiant percer
  RECOUTERA : du verbe recouter (couter à nouveau)
  ANORDIRAS : du verbe anordir (tourner au nord)
  SERIERONS : du verbe sérier (classer)
  ENDURANTE : de l'adjectif endurant (qui endure)
  STEMASSES : du verbe stemer ou stemmer (faire un stem au ski)

*** Figure 2 : 9-By-8 crossword puzzle created in 2004 by Jean-Charles Meyrignac [ECK, A near-perfect French 9-By-8 word rectangle][WIK, Mots croisés].
Horizontally:
  DECROCHES : de l'adjectif décroché
  ECOEURANT : de l'adjectif écoeurant
  RONFLANTE : de l'adjectif ronflant
  ATTRISTER : du verbe attrister
  PARAPHERA : du verbe parapher
  EMACIERAS : du verbe émacier
  REITERAIS : du verbe réitérer
  ASSENASSE : du verbe asséner
Vertically:
  DERAPERA : du verbe déraper
  ECOTAMES : du verbe écôter (enlever la côte des feuilles de certains légumes)
  CONTRAIS : du verbe contrer
  REFRACTE : du verbe réfracter
  OULIPIEN : de l'adjectif oulipien (relatif à l'oeuvre littéraire Oulipo)
  CRASHERA : du verbe crasher
  HANTERAS : du verbe hanter
  ENTERAIS : du verbe enter
  STERASSE : du verbe stérer

Word squares (1 10-By-10 and 48 9-By-9 word squares, partial display) :

* Figure 1 : 10-By-10 word square published in 1977 in the book "Jeux de lettres, jeux d'esprit" by Michel Laclos [GRA, Ars-magna].
  REMEURTRIE : du verbe remeurtrir
  ETABLERENT : du verbe établer (mettre à l'étable)
  MATOU VESTE : phrase : matou vesté, le second mot signifiant habillé ou appréhendé en vieux français, ou ennivré en dialecte génevois.
  EBOULASSES : du verbe ébouler
  ULULASSENT : du verbe ululer
  REVASSANTE : de l'adjectif rêvassant
  TRESSAUTER : du verbe tressauter
  RESSENTIRA : du verbe ressentir
  INTENTERAI : du verbe intenter
  ETESTERAIS : du verbe étester (forme ancienne du verbe étêter)

* Figure 2 : 9-By-9 word square published in 1975 in "Pratique des Mots Croisés" by Roger La Ferté and Jacques Capelovici (Que sais-je ? n° 1624) [CRU].
  TRAMERIEZ : du verbe tramer
  REDEPENDE : du verbe redépendre
  ADONISTES : botanistes spécialistes des plantes cultivées ou exotiques
  MENASSENT : du verbe mener
  EPISTANTE :
         1. Adjectif verbal féminin pouvant signifier broyante (mais non officiel en français) et formé sur le verbe épister signifiant broyer ou piler (terme de pharmacie) ;
         2. Participe présent (et adjectif verbal) du verbe portugais epistar signifiant broyer ou piler (terme de pharmacie) ;
         3. Nom du tableau "Epistante, 2019" peint par Simone Pelligrini, artiste dont l'atelier est à Bologne en Italie.
  RESSAUTER : du verbe ressauter
  INTENTERA : du verbe intenter
  EDENTERAI : du verbe édenter
  ZESTERAIS : du verbe zester

* Figure 3 : 9-By-9 word square published in 1977 in the book of Guy Brouty "Les Mots Croisés, toute une histoire" (Hachette) [CRU]. See [CHA].
  BRASSAMES : du verbe brasser
  REMEUVENT : du verbe remouvoir
  AMARRANTE :
         1. Erreur d'orthographe courante pour le nom amarante, plante relative au genre botanique Amaranthus. Cette faute se trouve souvent dans les articles culinaires.
         2. Adjectif verbal féminin pouvant signifier captivante, attachante ou qui amarre (mais non officiel en français) et formé sur le verbe amarrer ;
         3. Personnage "Amarrante" de la série d'albums pour enfants "Les Florafées" créée par H.F. Diané ;
         4. Deux villas de vacances "Borgo Amarrante" et "Molino di Amarrante" situées à Montaione en Toscane (Italie) ;
         5. Participe présent du vieux verbe italien amarrare signifiant amarrer.
  SERPENTER : du verbe serpenter
  SUREXCITA : du verbe surexciter
  AVANCERAS : du verbe avancer
  MENTIRONS : du verbe mentir
  ENTETANTE : de l'adjectif entêtant
  STERASSES : du verbe stérer

*** Figure 4 : 9-By-9 word square produced in 2007 by Christophe Lecoutre and Sébastien Tabary [LGD, Les Carrés symétriques-4].
  SACCAGENT : du verbe saccager
  AEROLOGIE : du nom aérologie
  CRAINDRAS : du verbe craindre
  COITERAIT : du verbe coïter
  ALNELOISE : de l'adjectif alnélois (relatif aux habitants de la commune d'Auneau en Eure-et-Loir)
  GODRONNER : du verbe godronner (border de godrons)
  EGRAINERA : du verbe égrainer
  NIAISERAI : du verbe niaiser
  TESTERAIS : du verbe tester

*** Figure 5 : 9-By-9 word square produced in 1996 by Laurent Bartholdi [WIK, Carré magique][WIK, Mots croisés] and communicated by Patrick Jenty [LGD, Symmetrical Squares-4].
  PACTISENT : du verbe pactiser
  ACHEMINER : du verbe acheminer
  CHARMERAI : du verbe charmer
  TERRIGENE : de l'adjectif terrigène (qui provient de l'érosion des terres)
  IMMINENTS : de l'adjectif imminent
  SIEGERAIT : du verbe siéger
  ENRENASSE : du verbe enrêner (mettre les rênes)
  NEANTISER : du verbe néantiser
  TRIESTERS : composés organiques possédant trois fois la fonction ester

*** Figure 6 : 9-By-9 word square produced in 1996 by Laurent Bartholdi [WIK, Carré magique][WIK, Mots croisés] and communicated by Patrick Jenty [LGD, Symmetrical Squares-4].
  PRECAIRES : de l'adjectif précaire
  REDONNENT : du verbe redonner
  EDENTASSE : du verbe édenter
  CONCILIER : du verbe concilier
  ANTISIGMA : lettre en forme de sigma renversé
  INALIENES : de l'adjectif inaliéné
  RESIGNONS : du verbe résigner
  ENSEMENCE : du verbe ensemencer
  STERASSES : du verbe stérer

*** Figures 7, 8 and 9 : 6 9-By-9 word squares (with alternatives) produced in 2007 by Brice Allenbrand [LGD, Les Carrés symétriques-4][ALL].
  Grille CABOSSERA
  Grille CASEMATER : Trois variantes sont possibles en remplaçant Z par E, R ou S dans RESSASSEZ
  Grille CRAMPERAS

*** Figures 10 then 11 to 22 : 37 9-By-9 word squares (with alternatives) produced in 2008 by Brice Allenbrand [LGD, Les Carrés symétriques-3][LGD, Les Carrés symétriques-2][LGD, Les Carrés symétriques-1].
  Grille ACCAPARER : Trois variantes sont possibles en remplaçant le R final par E, S ou Z dans RESSASSER
  Grille ARECACEES
  Grille ARRIVERAS
  Grille CHAMBRIER
  Grille CHASSABLE
  Grille CLASSABLE
  Grille CRAVACHEE
  Grille CRETACEES
  Grille EMECHASSE : Cinq variantes sont possibles en remplaçant le premier T par C dans ENTARTANT, et/ou U par D ou T dans ATTENUONS
  Grille EPERVIERE : Cinq variantes sont possibles en remplaçant C par T dans ENCARTONS, ou (C par S dans ENCARTONS, et premier N par S dans PUNEENNES), ou N par I dans ESSARTONS (en ligne horizontale et/ou verticale)
  Grille RAFRECHIS : Deux variantes sont possibles en remplaçant le deuxième T par R ou S dans INTERDITE
  Grille REGLABLES
  Grille RELACHERA : Neuf variantes sont possibles en remplaçant L par M dans RELACHERA (en ligne horizontale et/ou verticale), et/ou troisième S par I dans ASSONASSE (en ligne horizontale et/ou verticale)

B3.2. English crossword puzzles :

Word squares (1 12-By-12, 3 11-By-11 and 164 10-By-10 word squares, partial display) :

* Figure 1 : 12-By-12 word square produced in 2009 by Jeff Grant.
This square uses six tautonymous words [GRA, Some of my favorite squares].
  ENDING-ENDING : noun : the conclusion of the last part of a movie, play, book, etc.
  NGONGO-NGONGO : proper noun :
         1. Locality, Bengo Province, Angola, 8°1'S, 14°32'E
         2. Stream, Sangha region, Congo, 1°33'N, 15°41'E
  DOOGOO-DOOGOO : noun : variant of dugu-dugu, the sex act, or to have sex, in modern Jamaican English slang.
  INGENS INGENS : phrase : Megascops ingens ingens, subspecies of South American Rufescent Screech-Owl.
  NGONGENGONGE : noun : clipped person in New Zealand Maori.
  GOOSEY-GOOSEY : noun : variant of goosey, a foolish person, a simpleton, for example in the well-known English nursery rhyme "Goosey-Goosey Gander".

* Figure 2 : 11-By-11 word square produced in 1987 by Jeff Grant [GRA, Quasi eleven-squares].
This square includes proper.
  CENTIGRADES : noun : thermometers using the centigrade scale.
  EX-ORGUE RIMU : phrase : a nonce-term describing rimu wood formerly used in an orgue. 'Orgue' is defined as 'any of a number of long, thick timbers, pointed and shod with iron, formerly suspended over, or in the vaulted passage behind, a gateway, to be let down in case of attack; also, these pieces collectively'.
  NOMINATIVES : noun : words in the nominative case, in grammar.
  TRITICALITY : noun : triteness.
  IGNICOLISTS : noun : worshippers of fire.
  GUACONISING : noun : variant form of 'guaconizing', treating with guano.
  RETALIATORY : adj. : tending to, involving, or of the nature of, retaliation.
  ARI LISTENER : phrase : a listening person from the small community of Ari, Indiana. For example, a conversation between a resident of Ari, and one from Fort Wayne (12 miles away) could involve a Fort Wayne speaker and an 'Ari listener'.
  DIVISIONIST : noun : an advocate of the painting method known as divisionism.
  EMETT 'N RESCH : phrase : Emett and Resch are both surnames Iisted in the 1983 Melbourne, Australia, telephone directory. The form 'n is shown in Webster's Third Edition as a shortening of 'and'.
  SUSY'S GYRTHS : phrase : a nonce-term describing the refuges of someone named Susy, back in olden times. 'Susy' is shown in What to Narne the Baby, by Evelyn Wells, as a diminutive of 'Susan'. 'Gyrth' is an obsolete form of 'grith', a refuge or sanctuary.

* Figure 3 : 11-By-11 word square produced in 2004 by Rex Gooch [GOO, The eleven-square - Take one].
This square includes foreign terms and double names associated with American first and last names.
  AABD ES SALAM : proper noun : Aabd es Salam, Syria, 36°45'N, 40°17'E
  AARON CORONA : proper noun : Aaron Corona is the U.S. Marine Corps Lance Cpl., a protective security detail team member with 3rd Battalion, 7th Marine Regiment.
  BRENDAN RUDD : proper noun : Brendan Rudd lives in Star, Idaho.
  DON FERREIRA : proper noun : Don Ferreira lives in Brentwood, California, or in Klamath Falls, Oregon.
  ENDEUTESSEN : conjugated verb : from Catalan verb endeutar-se (third person plural of the imperfect subjunctive) meaning to get into debt.
  SCARTAITELE : conjugated verb : from Romanian verb a scartai (second person singular of the imperfect indicative) meaning to creak.
  SONREIREMOS : conjugated verb : from Spanish verb sonreir (first person plural of the futur indicative) meaning to smile.
  ARRESTEREND : conjugated verb : from Deutsch verb arresteren (present participle) meaning to arrest.
  LOUISE MEADE : proper noun : Louise Meade lives in Lebanon, Indiana, or in Xichita, Kansas.
  ANDRE LONDON : proper noun : Andre London lives in Douglasville, Georgia.
  MADANE'S DENS : phrase : Madane's dens is a manufactured phrase. Madane is a locality in Oio region, Guinea-Bissau, 12°11'N, 15°19'W

* Figure 4 : 11-By-11 word square produced in 2005 by Rex Gooch [GOO, The eleven-square - Take two][GRA, Some of my favorite squares].
This square includes foreign terms and double names associated with first and last names.
  MORRIS MOSES : proper noun : Sir Morris Moses (1762-1830), later called Captain Ximenes. An alternative squares uses Norris-Moses, surname of American representational artist Dorothy NORRIS-MOSES [GRA, Some of my favorite squares].
  ORIENTIRANI : verbal adj. : oriented in Slovenian.
  RIMISURANTI : conjugated verb : from Italian verb rimisurare (present participle) meaning to remeasure.
  REID PAINTER : proper noun : Reid Painter, a pupil recorded on the 5th grade Elementary "A/B" Honor Rolls for October 2003 and January 2004 in North Chatham School, Chatham County, North Carolina.
  INSPIRADORS : noun : inspirators in Catalan.
  STUART MASON : proper noun : Dr Stuart Mason, English endocrinologist (1919-2003). A second alternative squares uses Stuart Mahon (a redident of Dublin, Ireland) and Santo Helier (a Spanish version of the name of the 6th century ascetic hermit (St. Heller), and also the capital of Jersey in the Channel Islands, which is named after him) [GRA, Some of my favorite squares].
  MIRIAM GRECO : proper noun : Miriam Greco and her husband David sold a property at 343 Barclay St, Burlington County, Philadelphia, around January 2004.
  ORANDARILOR : noun : from Romanian noun orandar (genitive or dative plural form) meaning someone who owns an inn.
  SANTOS ELLER : double proper noun : a Brazilian double surname. A Brazilian website devoted to the genealogy of the Eller family records "Maria dos SANTOS ELLER (born 3 June 1932)".
  ENTEROCOELE : noun : the body cavity formed from an outpocketing of the archenteron (a primitive digestive cavity), especially typical of echinoderms and chordates.
  SIERSNORREN : proper noun : a contrived Dutch meaning something like ostentatiously-decorated moustaches, formed by combinig sier (decorative or ornamental) with snorren (moustaches).

*** Figure 5 : 10-By-10 word square produced in 2023 by Matevz Kovacic, Sloveny [KOV][CAM].
All ten words are unique common nouns.
  SCAPHARCAE : adj. : specific epithet of bacterium name Ornithinibacillus scapharcae
  CERRATEANA : adj. : specific epithet of plant name Pitcairnia cerreteana
  ARGOLETIER : noon : a light mouted soldier ; a mounted bowman
  PROCOLICIN : noon : a propeptide form of colicin
  HALOBORATE : noon : a type of inorganic compound
  ATELOMERES : adj. : specific epithet of moth name Ectropis atelomeres
  RETIREMENT : noon : withdrawal from one's position or occupation or form active working live
  CAICARENSE : adj. : specific epithet of plant name Machaerium caicarense
  ANEITENSIS : adj. : specific epithet of tree fern name Alsophila aneitensis
  EARNESTEST : adj. : superlative form of earnest

* Figure 6 : 10-By-10 word square produced in 2006 by Jeff Grant [GRA, FISCALISED ten-square revisited][GRA, The best ten-squares].
  FISCALISED : verbal adj. : variant of fiscalized
  IMPOLARITY : noun : absence of polarity
  SPALACINES : noun : blind mole-rats of the subfamily Spalacinae
  COLDNOSERS : noun : slang for hunting dogs that follow cold trails
  ALAN BROWNE : proper noun : an American bank consultant (1908-88), in Who's Who in America, 45th Ed., 1988-89.
  LA CORALINA : proper noun : locality located in the town of Candelaria, Artemisa province, Western Cuba, 22°45'N, 82°57'W
  IRISOLONES : noun : colourless estrogenic compounds derived from certain irises
  SINEWINESS : noun : state or quality of being sinewy ; firm strength
  ETERNNESSE : noun : variant of eternness, eternity
  DYSSEASSES : noun : 16th century forms of the noun diseases

* Figure 7 : 10-By-10 word square produced in 1995 by Jeff Grant [GRA, A spooner-assisted ten-square].
  VASSALISED : verbal adj. : subdued, subjugated
  ANTELARITY : noun : a blend of antelation (preference, precedence) and priority attributed to the Reverend William Spooner when mixing up the words of 17th-century Spanish scholar James Mabber : "Alleging the antelarity of time, and priotion of his debt".
  STYRACINES : noun : white crystalline substances obtained from storax and balsam of Peru
  SERENADERS : noun : people who serenade, entertain with music
  ALAN BROWNE : proper noun : an American bank consultant (1908-88), in Who's Who in America, 45th Ed., 1988-89.
  LA CAROLINA : proper noun : town located in the Jaén province, Spain, 38°16'N, 3°37'W
  IRIDOLINES : noun : oily liquid compounds derived from coal-tar
  SINEWINESS : noun : state or quality of being sinewy ; firm strength
  ETERNNESS : noun : variant of eternness, eternity
  DYSSEASSES : noun : 16th century forms of the noun diseases

* Figure 8 : 10-By-10 word square produced in 1998 by Ted Clarke [CLA, A new Wordsworth word square][LAN].
  DISCUSSING : verbal noun : talking
  INCANTATOR : noun : one who uses incantation
  SCARLATINA : noun : scarlet fever
  CARNITINES : noun : enzymes that transport activated long-chain fatty acids across the mitochondrial membrane
  UNLIKENESS : adj. : of little ressemblance
  STATE'S WREN : phrase : little bird on flag of some US states (especially South Carolina)
  SATIN WEAVE : phrase : silk-like cloth.
  ITINERATES : conjugated verb : wanders aimlessly
  NONES EVENT : phrase : plausible festival of the ancient Romans
  GRASS NESTS : phrase : nests made by weaver birds for example

* Figure 9 : 10-By-10 word square produced in 2008 by Martin Laeuter [cf email of September 8, 2024 from Jean-Charles Meyrignac to Régis Petit].
  MADHAB PASA : proper noun : Madhab Pasa, village, babuganj upazila region, Bangladesh, 22°46'N, 90°17'E
  ARAEDAESIL : proper noun : Araedaesil, town, Chungcheongnam-do region, South Korea, 36°49'N, 126°58'E
  DAURAN NALA : proper noun : Dauran Nala, intermittent stream, Balochistan, Pakistan, 30°20'N, 67°23'E
  HERVIDEROS : proper noun : Los Hervideros, tourist site, Lanzarote island, Canary Islands, Spain, 28°57'N, 13°50'O
  ADAILE-KOMA : proper noun : Adaïlé-Koma, mountain, Djibouti, 11°29'N, 42°33'E
  BAND-E SIRAK : proper noun : Band-e Sirak, mountain, Wilayat-e Ghor Province, Afghanistan, 33°27'N, 65°7'E. An alternative square uses Band-e Zirak
  PENE-KIKILI : proper noun : Pene-Kikili, town, Maniema Province, Congo-Kinshasa, 4°36'S, 26°20'E
  ASARO RIVER : proper noun : Asaro River, river, Eastern Highlands Province, Papua New Guinea, 6°22'S, 145°12'E
  SILOMALELA : proper noun : Silomalela, village, Nias island, North Sumatra Province, Indonesia, 1°6'N, 97°39'E
  AL'ASAKIRAH : proper noun :
         1. Al'Asakirah, village, Dhamar Governorate, Yemen, 14°33'N, 44°40'E
         2. Al'Asakirah, village, Dhi Qar region, Irak, 31°0'N, 46°21'E
         3. Al'Asakirah, village, Bani Suwayf region, Egypt, 28°55'N, 30°53'E

* Figure 10 : 10-By-10 word square produced in 1973 by Dmitri Borgmann.
This square uses five tautonymous words [BOR, A new 100-letter word square][GRA, Ars-magna].
  RABBI, RABBI : phrase : included in the verse "And greetings in the markets, and to be called of men, Rabbi, Rabbi" in "Gospel According to Saint Matthew", Chapter 23, Verse 7 (cf "The New Testament and the Book of Psalms", King James Version, published by the American Bible Society (New York, 1972)).
  A SAIL ! A SAIL ! : phrase : included in the poetic quotation "I bit my arm, I sucked the blood, And cried, A sail ! a sail !" of Taylor Coleridge in "The Rime of the Ancient Mariner", Part III, Stanza 4 (cf "Familiar Quotations" by John Bartlett, 14th Edition, Revised and Enlarged, published by Little, Brown and Company (Boston and Toronto, 1968)).
  BASSA-BASSA : noun : general confusion, noise, and, in some cases, exchange of blows (cf "Notes for a Glossary of Words and Phrases of Barbadian Dialect" by Frank A. Collymore, published by Advocate Company (Bridgetown, Barbados, 1970)).
  BISON BISON : phrase : Bison bison, scientific (genus + species) name for the bison, a hoofed animal of western North America (cf "The American Heritage Dictionary of the English Language" edited by William Morris, published jointly by American Heritage Publishing Company, Inc., and Houghton Mifflin Company (Boston, New York, Atlanta, Geneva, Illionis, Dallas, Palo Alto, California, 1971)).
  ILANG-ILANG : noun : variant spelling of ylang-ylang, a tree native to the Phillippines, Java and India (cf "The World Book Dictionary" edited by Clarerce L. Barnhart, a Thorndike-Barnhart Dictonary published exclusively for Field Enterprises Educational Corporation (Chicago, London, Rome, Stockholm, Sydney, Toronto, 1968)).

* Figure 11 : 10-By-10 word square produced in 2002 by Rex Gooch [GOO, An A to Z of ten-squares][GOO, My first ten-square].
  ABAPTISTUM : noun : abaptiston (cone-shaped trephine)
  BAHRAMTAPA : proper noun : in Azerbaijan, 39°44'N, 47°57'E
  AHLERBRUCH : proper noun : in Germany, 52°12'N, 8°29'E
  PREPARATOR : noun : a person who prepares
  TARADANOVA : proper noun : in Russia, 54°45'N, 86°41'E. An alternative square uses Tarakanova, 55°21'N, 38°57'E, also in Russia.
  IMBRANGLES : conjugated verb : old form of embrangles
  STRANGFORD : proper noun : Strangford :
         1. Village, Herefordshire, England, 51°57'N, 2°37'W
         2. Farmstead, New Zealand, 43°16'S, 172°06'E
  TAUTOLOGIA : noun : Late Latin (or Greek), whence tautology
  UPCOVERING : verbal noun : old form of up covering
  MAHRAS DAGI : proper noun : Mahras Dagi in Turkey, 36°43'N, 33°17'E

* Figure 12 : 10-By-10 word square produced in 2003 by Rex Gooch [GOO, Ten-squares with place names].
  BACKSBACKA : proper noun : Backsbacka, Finland, 63°27'N, 23°07'E
  ANHUMINAS : proper noun : Ribeirao Anhuminhas, Brazil, 22°53'S, 50°50'W
  CHAHARGAL'A : proper noun : Chahargal'a-i-Wazirabad, Afghanistan, 34°33'N, 69°09'E
  KUH-E SHAHIN : proper noun : Kuh-e Shahin, Iran, 35°24'N, 46°32'E
  SMASVALENE : proper noun : Smasvalene, Norway, 60°58'N, 4°38'E
  BI'R HASANAH : proper noun : Bi'r Hasanah, Finland, 30°27'N, 33°46'E
  ANGALACANE : proper noun : Angalacane, Mozambique, 22°28'S, 31°31'E
  CHAH-E NASIR : proper noun : Chah-e Nasir, Iran, 27°43'N, 58°01'E
  KALINANINA : proper noun : Kalinanina, Zambia, 14°23'S, 24°44'E
  ASANE HERAD : proper noun : Asane Herad, Norway, 60°28'N, 5°25'E

* Figure 13 : 10-By-10 word square produced in 2003 by Rex Gooch [GOO, Ten-squares with place names].
  BAGANBATAK : proper noun : Baganbatak, Columbia, 3°12'N, 99°40'E
  'ARAB AR RAML : proper noun : 'Arab ar Raml, Egypt, 30°31'N, 31°12'E
  GARANYEMBE : proper noun : Garanyembe, Zambia, 14°25'S, 26°56'E
  ABAG KANALI : proper noun : Abag Kanali, Azerbaijan, 39°11'N,48°36'E
  NANKUNSHAN : proper noun : Nankunshan, China, 23°38'N, 113°53'E. An alternative square uses Nankan Shan, Taiwan, 25°04'N, 121°18'E
  BRYANT BANK : proper noun : Bryant Bank, an undersea feature, 28°01'N, 92°28'W
  ARENSBURGA : proper noun : Arensburga, Estonia, 58°14'N, 22°30'E
  TAMA HARBOR : proper noun : Tama Harbor, Japan, 34°28'N, 133°56'E
  AMBLANGODA : proper noun : Amblangoda, Sri Lanka, 7°00'N, 81°11'E
  KLEIN-KARAS : proper noun : Klein-Karas, Namibia, railroad siding, 27°34'S, 18°06'E

* Figure 14 : 10-By-10 word square produced in 2002 by Rex Gooch [GRA, The best ten-squares][GOO, Some superior ten-squares][CAM].
  DESCENDANT : noun : one descended from an ancestor ; issue, offspring
  ECHENEIDAE : noun : the remora family of fishes
  SHORTCOATS : noun : people wearing short coats
  CERBERULUS : adj. : specific epithet of ant name Camponotus cerberulus
  ENTEROMERE : noun : any segment of the embryonic alimentary tract
  NECROLATER : noun : someone who worships the dead or dead bodies
  DIOUMABANA : proper noun : a populated place in eastern Guinea, West Africa, 11°16'N, 9°08'W
  ADALETABAT : proper noun : a populated place in the Mus province, eastern Turkey, 38°58'N, 42°42'W
  NATURE-NAME : noun : a toponym (place name) embodying an allusion to a natural occurrence or geographical feature
  TESSERATED : verbal adj. : rare variant of tessellated, composed of small blocks of variously coloured material arranged to form a pattern

* Figure 15 : 10-By-10 word square produced in 2002 by Rex Gooch [GOO, Some superior ten-squares].
  DESSEMBLED : verbal adj. : come from the old French verb dissembler meaning to dissemble
  EL-TAMARANI : proper noun : Wadi el-Tamarani, Egypt, 29°52'N, 34°32'E
  STITCHINGS : verbal noun : activities of sewing individual threads in something
  SATIRETTES : noun : small satires
  EMCRISTENE : noun : old form of fellow Christian. An alternative square uses emcrystene
  MAHESWARDI : proper noun : Nagar Maheswardi, Bangladesh, 24°04'N, 90°42'E,
  BRITTAINES : noun : old form of Britons
  LANTERNARO : noun : lantern maker or seller (of Italian origin)
  ENGENDERER : noun : producer, causer or bringer
  DISSEISORS : noun : persons who wrongfully dispossess

* Figure 16 : 10-By-10 word square produced in 2002 by Rex Gooch [GOO, Some superior ten-squares].
The ten words are all without separators (space, period, hyphen or apostrophe).
  DISSAVAGED : verbal adj. : civilized
  IKHATARENE : proper noun : Ikhatarene, Morocco, 33°17'N, 4°44'W
  SHORTLINGS : noun : short or small persons
  SARARESTII : proper noun : Sararestii, Romania, 44°56'N, 24°52'E
  ATTRISTING : verbal noun : saddening
  VALESTOLEN : proper noun : Valestolen, Norway, 60°49'N, 5°32'E
  ARISTOTILL : proper noun : medieval form of the proper noun Aristotle
  GENTILITEE : noun : medieval form of the noun gentility
  ENGINELESS : adj. : without an engine
  DESIGNLESS : adj. : being without a design

* Figure 17 : 10-By-10 word square produced in 1990 by G.H. Ropes [ROP, Further struggles with a ten-square].
  JAS J. ASCHER : proper noun : name of James J. Ascher found in a Kansas City telephone directory
  AQUAMARINE : noun : transparent blue-green gemstone
  SUFFISANTS : noun : citation-word plural for the obsolete adjective suffisant meaning sufficient
  JAFFA'S FORT : phrase : old military structure located in Jaffa, Palestine
  AMIATA TIER : phrase : Amiata is a mountain in the Apennine range in central Italy, part of a long chain which could plausibly be named the Amiata Tier
  SASSANIDAE : proper noun : members of the native dynasty that built and ruled an empire in Persia from 224 to 636
  CRAFTINESS : noun : cunning
  HINOIDEOUS : adj. : with veins proceeding from the midrib parallel and unbranched (venation of the leaves)
  ENTREASURE : verb : to lay up in or as in a treasury
  RESTRESSED : adj. : stressed again

* 5 other 10-By-10 word squares produced in 1990 and 2002 by Jeff Grant.
These squares include foreign terms and double names associated with American first and last names. See [GRA, A modified ten-square][GRA, In search of the ten-square].
  1 ASTRALISED square
  1 DISTALISED square
  1 DORAASCHER square
  1 INCAPABLER square
  1 MISSATICAL square

* 35 other 10-By-10 word squares (with alternatives) produced in 2003 by Rex Gooch.
These squares begin with each letter of the alphabet including separators (space, period, hyphen or apostrophe). See [GOO, An A to Z of ten-squares].
  1 BANPAKKHEN square
  1 CILASTATIN square
  2 EPICOPARI squares
  1 FABODTRASK square
  1 GATSCHAPAR square
  2 HARADSMALA squares
  1 IMPRESSUS square
  1 JASTREBACA square
  1 KACHIKAMAR square
  1 LATCHESNES square
  1 MACABABALO square
  1 MAIDENPAPS square
  1 MALENESSES square
  1 NISISASPRO square
  1 OCHIRIKROM square
  1 OMIMICREEK square
  1 PARADISIAL square
  2 PASSAGE-BED squares
  1 QALA'-I-NAMAK square
  1 RESISTLESS square
  2 SPASMODISM squares
  1 TANAMALALA square
  1 UNTUNNELED square
  1 VALEAHOGEA square
  1 WADIEL'EISH square
  1 WADIGHABAT square
  1 WALSHOUTEM square
  1 XOMBANTANG square
  2 YATTAWATTE squares
  1 ZUSAMMFALL square

* 108 other 10-By-10 word squares (with alternatives) produced in 2003 by Rex Gooch.
These squares use five tautonymous or quasi-tautonymous words. See [GOO, Quarter ten-squares].
  10 ABANGABANG squares
  12 ALANGALANG squares
  18 ANTINANTIN squares
  5 CLANGCLANG squares
  1 HANGIHANGI square
  1 ILANGILANG square
  27 INGITINGIT squares
  1 MANGIMANGI square
  2 ORANGOTANG squares
  1 ORANGUTANG square
  1 RENGARENGA square
  1 SANGASANGA square
  1 SANGISANGI square
  1 TANGITANGI square
  21 UNGASUNGAS squares
  1 URANGUTANG square
  1 WALLAWALLA square
  1 WANGIWANGI square
  1 WHANGWHANG square
  1 YLANGYLANG square

* 3 other 10-By-10 word squares (with alternatives) produced in 2004 by Rex Gooch.
These squares include separators (space, period, hyphen or apostrophe). See [GOO, Hunting the ten-square].
  2 NOSTOCACEA square
  1 UORESPECHE square

B3.3. Italien crossword puzzles :

Word squares (1 8-By-8 word square) :

*** 1 8-By-8 square published in 1965 by Dmitri Borgmann [BOR, Language on Vacation, p.198].
  STACCATA : verbal adj. : detached
  TOREADOR : noun : bullfighter ; the more usual Italian word, however, is "toreadore".
  ARISTONE : noun : kind of hand organ
  CESSERAN : conjugated verb : poetic form of cesseranno meaning (they will) cease, which can be found in opera librettos
  CATENATA : verbal adj. : chained
  ADORATOR : noun : adorer
  TONATORI : noun : thunderers
  ARENARIO : adj. : sandy

B3.4. Spanish crossword puzzles :

Word squares (1 8-By-8 word square) :

*** 1 8-By-8 square published in 1965 by Dmitri Borgmann [BOR, Language on Vacation, p.198].
  PASAJERA : noun : female traveler
  ABATANAR : from the verb abatanar (infinitive form) meaning full cloth
  SATIRAZA : noun : fat, witty woman
  ATINARON : from the verb atinar (third person plural simple past form) meaning hit the mark : (they) hit the mark
  JARAMENA : feminine adj. : related to Jarama River in Spain. Example of use : "La ganaderia jarameña de toros"
  ENARENAR : from the verb enarenar (infinitive form) meaning cover with sand
  RAZONABA : from the verb razonar (third person singular imperfect form) meaning reason : (he) was reasoning
  ARANARAS : from the verb arañar (second person singular imperfect subjunctive form) meaning scratch : (that you) would scratch, or (that you) would scratch, or (if you) scratched, or (if you) were to scratch

B3.5. Latin crossword puzzles :

Word squares (two 11-By-11 word squares) :

*** Figure 1 : 11-By-11 word square published in 2020 by Eric Tentarelli [TEN].
Warning: this square contains a typo in the display : the second R of the horizontal word STERILITARI must be changed to T [RPR].
  RESCISSEMUR : from the verb rescisso (first person plural future passive form) meaning discover (something unexpected)
  EXTENTERARE : from the verb extentero (infinitive form) meaning disembowel
  STENDERESIS : from the verb stendo (second person singular imperfect passive subjunctive form) defined as an apheretic form of extendo, a versatile verb whose primary meaning is extend or stretch out.
  CENSEREMINI : from the noun censeo (second person plural imperfect passive subjunctive form) meaning value, esteem
  INDEFINITAM : from the adjective indefinitus (feminine accusative singular form) meaning indefinite
  STERILITATI : from the noun sterilitas (dative singular form) meaning sterility
  SERENITATIS : from the noun serenitas (genitive singular form) meaning serenity. This particular inflected form may be familiar because Mare Serenitatis is one of the most visible features on the Moon.
  EREMITARIOS : from the adjective eremitarius (masculine accusative plural form) meaning living a hermit's life
  MARITATIONI : from the noun maritatio (dative singular form) meaning wedding or marriage
  URINATIONEM : from the noun urinatio (accusative singular form) meaning urination
  RESIMISSIMI : from the adjective resimus (masculine genitive singular of the superlative form) meaning turned up or bent back, which typically describes noses.
An alternative square is to change EXTENTERARE to EXTENTERATE (second person plural present imperative form of the same verb) and URINATIONEM to UTINATIONEM (accusative singular form of the noun utinatio meaning wish or expression of a wish).

*** Figure 2 : 11-By-11 word square published in 2020 by Eric Tentarelli [TEN].
  SCISSURAMUR : from the verb scissuro (first person plural present passive form) meaning cut (cloth, as to make garments)
  CONTENERARE : from the verb contenero (infinitive form) meaning make tender
  INFAMATORIS : from the noun infamator (genitive singular form) meaning slanderer
  STAMINAMINI : from the verb stamino (second person plural present passive form) meaning spin (thread) or support (a vine) with stakes
  SEMILIMATAM : from the adjective semilimatus (feminine accusative singular form) meaning half-polished
  UNANIMITATI : from the noun unanimitas (dative singular form) meaning unanimity
  RETAMINATIS : from the verb retamino (second person plural present form) meaning befoul, particularly with excrement
  AROMATARIOS : from the noun aromatarius (accusative plural form) meaning dealer in spices or apothecary
  MARITATIONI : from the noun maritatio (dative singular form) meaning wedding or marriage
  URINATIONEM : from the noun urinatio (accusative singular form) meaning urination
  RESIMISSIMI : from the adjective resimus (masculine genitive singular of the superlative form) meaning turned up or bent back, which typically describes noses.

B3.6. Serbian crossword puzzles :

Word squares (2 10-By-10 word squares) :

These squares, together with the Croatian squares of Anton Ferderber and Boris Babic, were published in 1999 by Miroslav Lazarevic [NAZ][ECK, The polyglot ten-square].

* 1 10-By-10 word square published in 1987 by Miroslav Lazarevni [NAZ][ECK, The polyglot ten-square][TWO]. Translation by [PER].
  SAMONAMENA : noun :
         1. sole purpose
         2. unique destination
         3. exclusive intent
  ANIMALIZAM : noun : animalism
  MILADINOVO : proper noun :
         1. Miladinovo Brdo, hill, 44°04'N, 21°28'E, located near the village of Balajnac, Despotovac Municipality, Pomoravlje district, Serbia.
         2. Miladinovo, village, Kardzhali Municipality, Kardzhali Province, Bulgaria, 41°42'N, 25°36'E
  OMANJI SITAR : phrase : little sitar
  NADIZATELJI : noun : those who surprise from above ?
  ALISA MARICH : proper noun : Serbian chess player and Minister of Youth and Sports in the Serbia Government in 2012
  MINI TALJIVA : phrase : miniature dissolving object ?
  EZOTERICHAN : adj. : esoteric
  NAVALJIVATI : verb : to push, to insist
  AMORICHANIN : noun : devotee of Cupid ?

* 1 10-By-10 word square published in 1996 by Zivota Stankovic [NAZ][ECK, The polyglot ten-square][TWO]. Translation by [PER].
  KAMATARINA : adj. : usurer's
  ABUSALATIN : noun : another name for the plant Ricinus communis. This term comes from the Arabic "habb" (grains) and "sultan" (sultan) which refers to the "grains of the sultans" (see https://jezikoslovac.com/ ).
  MUNARANINI : noun : little minaret ?
  ASALAMINIJ : phrase : and the salamis for me ?
  TARASIJEVA : adj. : Tarasije's (Tarasije = Serbian form of the Greek first name Tarasios of Constantinople)
  ALAMINARIN : adj. : without laminarin (laminarin = polysaccharide of brown algae)
  RANI JANJANI : phrase :
         1. ancient Janjani (Janjani = locality, Srebrenik Municipality, Republika Srpska, Bosnia and Herzegovina, 42°13'N, 17°28'E)
         2. early Janja inhabitants (Janja = locality, Bijeljina Municipality, Republika Srpska, Bosnia and Herzegovina, 44°40'N, 19°15'E)
         3. early Janja supporters (Janja = Janja Bec Neumann, Serbian sociologist and genocide researcher, Nobel Peace Prize winner in 2005)
  ITINERARIJ : noun : itinerary
  NINIVINICA : phrase : not even a small wine ?
  ANIJANIJAC : noun : little spell ? (anijanij = a spell in Marshall islands language)

B3.7. Croatian crossword puzzles :

Word squares (2 11-By-11 and 6 10-By-10 word squares, partial display) :

* 1 11-By-11 word square produced in 2015 by Milutin Tepsic [SRP]. Translation conforms to the definitions of this square [SRP].
  KAPETANIJAC : noun : the man who lives in the captaincy
  ANATOMIKOVI : noun : those who belong to an academician (= anatomist's group ?)
  PAZI NA SHANAC : phrase : the soldier, a guard in the trench (ditch) (= watch the trench ?)
  ETIKETARINA : noun : the fee that is paid for affixing labels
  TONEVERIZAM : noun : Verism heavy as thunder
  AMATERIJALI : adj. : immaterials
  NISHARINARAC : noun : the toll collector of the Nichava bridge
  IKARIJASHITI : verb : to fly too close to the sun
  JONIZARIZAM : noun : doctrine advocating widespread ionization
  AVANALATARI : noun : mortar tool manufacturers
  CICA MICI MISH : phrase : the modern form of the saying "Render unto Cesar what is Cesar's, to God what is God's - literally, "to the cat what it likes most to hunt" (= to the kitty its mouse ?)

* 1 11-By-11 word square produced in 2015 by Zarka Dokica [CVE]. Translation conforms to the definitions of this square [CVE].
  ARI PALEVSKI : proper noun : collaborator on the film "Virginity" (2014) directed by Saeed Khoze.
  ROSANA GITAN : proper noun : compound female name, the namesake of the Swedish actresses Munter and Goding.
  ISPREBASATI : verb : to break out
  PARAMOLORAC : noun : resident of Paramo Lora region, Cantabria Province, Spain.
  ANEMARI KIRI : proper noun : Austrian humanitarian and author of the book "My Unusual Journeys - Steps of Hope" about her experiences in the 1991-1995 war.
  LABORATORIJ : noun : laboratory
  EGALITIRANA : verbal adj. : equalized
  VISOKORODAC : noun : vegetable plants with tall trees or stems, for example corn.
  STARI RADARI: phrase : obsolete radio-locators
  KATARINA ROJ : proper noun : a young member of the women's hockey club "Boston Samrocks"
  INICIJACIJA : noun : customs and rites (almost among all primitive peoples) by which a boy is declared a boy, and a girl a girl.

* 1 10-By-10 NASTRANOST word square produced in 1941 by Anton Ferderber [DNE][NAZ].
* 1 10-By-10 NADPRILIKA word square produced in 1984 by Boris Babic [BLO][NAZ].
* 1 10-By-10 PERIPATUSI word square produced in 1987 by Boris Babic [ENI][NAZ].
* 1 10-By-10 TIPSKAZENA word square produced in 2010 by Antun Cvitkovic [DNE][DNE2][NAZ].
* 1 10-By-10 OSTANIDOMA word square produced in 2020 by Boris Babic, Resad Besnicanin, Zarko Dokic, Antun Juric, Nedjeljko Nedic, Ilija Ozdanovac and Georgi Zeravica [DOM].
* Other 10x10 word squares including that of Zarka Dokica [CVE].

B3.8. Hungarian crossword puzzles :

Classic crossword puzzles (1 9-By-9 crossword puzzle) :

* 1 9-By-9 crossword puzzle published by CPT [CPT]. Translation by [PER].
Horizontally :
  KI SZELNEK : phrase : "who are cutting ?"
  RAZAROEBA : ?
  IZEGOKNEK : ?
  SAROSIIDE : adj. : Saros's (Saros = former department of Hungary, 49°00'N, 21°14'E)
  ZSEREITEK : adj. : Zsére's (Zsére = another name for Zirany, Nitra region, Slovakia, 48°23'N, 18°10'E)
  TINIITEKE : phrase : to your teenagers
  ABANDOKEN : ?
  BANKEKERA : phrase : towards the bank group ?
  ANKETENEK : phrase : for his/her survey
Vertically :
  KRISZTABA : phrase : into Kriszta (Kriszta = diminutive of Krisztina)
  IAZASIBAN : phrase : while braying
  SZERENANK : ?
  ZAGORINKE : proper noun : Zagorin's ?
  EROSEIDET : phrase : your strong ones ?
  LOKI I TOKE : phrase ? : the Loki bow and its arrow rest ?
  NENITEKEN : phrase : on your aunt
  EBEDEKERE : phrase : towards your lunches ?
  KAKEKENAK : ?

B3.9. Hebrew crossword puzzles :

Classic crossword puzzles (1 10-By-10 crossword puzzle) :

* 1 10-By-10 crossword puzzle published by CPT [CPT]. Partial list of words translated by [PER] :
Horizontally :
  1- she shoshbinotayikh : phrase : "who are her bridesmaids ?"
  12- keshelkhem yirkhtu : phrase : when it belongs to you, they buy it
  19- ve se ototeihem : phrase : and that theirs signs
Vertically :
  1- shel keshe shukhlelu : phrase : of when they were perfected
  10- ha havayati'im : phrase : the experiential aspects

Sources relating to crossword puzzles :

• [ALL] Brice Allenbrand : page principale, 2002
• [BLO] Blogspot, 2023
• [BOR] Dmitri A. Borgmann, A new 100-letter word square, 1973
• [BOR] Dmitri A. Borgmann, Language on Vacation, Charles Scribner's Sons, 1965
• [CAM] T. Campbell, The Holy Grail of Logology, 2024
• [CHA] C. Chaplot, La théorie et la pratique des jeux d'esprit, 1895-1905
• [CLA] Ted Clarke, A new Wordsworth word square, 1998
• [CPT] Crossword Power Tools - CPT Collection, 10 Aug 2017
• [CRU] cruci.com, Le lexique des mots croisés
• [CVE] Magcni kvadrat 11x11 Zarka Dokica
• [DNE] blog dnevnik, 2018
• [DNE2] blog dnevnik - definitions, 2018
• [DOM] Dominikanac, 2020
• [DRI] Jacques Drillon, Les mots croisés ont 100 ans : les cases du siècle, Le Nouvel Obs, 2013
• [ECK] A. Ross Eckler, A near-perfect French 9-By-8 word rectangle, 2007
• [ECK] A. Ross Eckler, The polyglot ten-square, 2004
• [ENI] Enigmaticatio, 2020
• [GOO] Rex Gooch, My first ten-square, 2002
• [GOO] Rex Gooch, Some superior ten-squares, 2002
• [GOO] Rex Gooch, Ten-squares with place names, 2003
• [GOO] Rex Gooch, An A to Z of ten-squares, 2003
• [GOO] Rex Gooch, Quarter ten-squares, 2003
• [GOO] Rex Gooch, Hunting the ten-square, 2004
• [GOO] Rex Gooch, The eleven-square - Take one, 2004
• [GOO] Rex Gooch, The eleven-square - Take two, 2005
• [GRA] Jeff Grant, Ars-magna : the ten-square, 1985
• [GRA] Jeff Grant, Quasi eleven-squares, 1987
• [GRA] Jeff Grant, In search of the ten-square, 1990
• [GRA] Jeff Grant, A spooner-assisted ten-square, 1995
• [GRA] Jeff Grant, A modified ten-square, 2002
• [GRA] Jeff Grant, A further modified ten-square, 2004
• [GRA] Jeff Grant, The best ten-squares, 2006
• [GRA] Jeff Grant, Some of my favorite squares, 2009
• [GRA] Jeff Grant, FISCALISED ten-square revisited, 2019
• [KOV] Matevz Kovacic, Word square
• [LAN] Langage Log, 2005
• [LGD] Le Grand Défi des mots croisés, Accueil, 2011-2023
• [LGD] Le Grand Défi des mots croisés, Accueil idem
• [LGD] Le Grand Défi des mots croisés, Historique
• [LGD] Le Grand Défi des mots croisés, Les Carrés symétriques-4 (6 grilles Lecoutre, Jenty et Allenbrand)
• [LGD] Le Grand Défi des mots croisés, Les Carrés symétriques-3 (Grilles Allenbrand n°10 à 24)
• [LGD] Le Grand Défi des mots croisés, Les Carrés symétriques-2 (Grilles Allenbrand n°25 à 39)
• [LGD] Le Grand Défi des mots croisés, Les Carrés symétriques-1 (Grilles Allenbrand n°40 à 54)
• [LGD] Le Grand Défi des mots croisés, Les Carrés symétriques-1 idem (Grilles Allenbrand n°40 à 54)
• [NAZ] Boris Nazanski, Magicni kvadrat 10×10, 2010
• [PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
• [ROP] G.H. Ropes, Further struggles with a ten-square, 1990
• [RPR] r/programming
• [SRP] Srpska Enigmatika
• [TEN] Eric Tentarelli - Large Word Squares in Latin, 2020
• [TNP] The National Puzzlers' League, 2022
• [TWO] Two word squares in Serbian
• [WIK] Wikipedia - Mots croisés
• [WIK] Wikipedia, Carré magique (lettres)
• [WOR] Word ways, Butler University

C. Natural sciences

C1. Climat change

This chapter explores key aspects of climate change, including the role of the IPCC, the controversy surrounding the topic, greenhouse gases, individual and collective carbon footprints, and potential impacts and solutions to help us better understand how to address this global challenge.

1. Definition
2. IPCC
3. Controversy
4. Greenhouse gas
5. Carbon footprint
6. Impacts
7. Solutions
8. Sources

  

C1.1. Definition :

Climate change, also called "global warming", is the significant increase in the average temperature of the earth's surface since the beginning of the 20th century.
Be careful not to confuse "climate" and "weather". Weather refers to the weather over a short period (a day, a week). Climate refers to past and future time over long periods (year, century, millennium).

The graph above in left Figure shows that this increase (from 1900 to 2019) is unprecedented in the last 2000 years. The graph is a reconstruction including data from a wide variety of records such as tree rings, cave deposits, corals, etc. Added some relevant world events such as major volcanic eruptions, the Maunder Solar Minimum and historical dates of scientific discoveries. The oft-cited Medieval Warm Period and Little Ice Age are real phenomena, but small compared to recent changes [HAW].
Caption : Evolution of the global average annual temperature of the earth's surface from year 1 to 2019, relative to the pre-industrial reference (1850-1900) [HAW].

The graph above in right Figure shows that the decade 2011-2020 was 1.1 °C warmer than the pre-industrial reference (1850-1900), with warming being greater on the continents (+1.6 °C) than in above the oceans (+0.9 °C) [TSP][GIE][MTE3].
Caption : Evolution of the global average annual temperature of the earth's surface from 1850 to 2020, relative to the pre-industrial reference (1850-1900) [MTE3]. The connected dots show the data year by year. The solid black curve is a rolling average of the annual totals over 11 years (average of years N-5 to N+5 for year N) making it possible to overcome the modulation due to the cycle of solar activity (11 years) [POI].

C1.2. IPCC :

The IPCC (Intergovernmental Panel on Climate Change) is a scientific body created in 1988, responsible for assessing the extent, causes and consequences of ongoing climate change.
The IPCC position confirms this warming and attributes it unequivocally to greenhouse gas (GHG) emissions of human origin, called "additional or additive or anthropogenic greenhouse effect" [WIK1].
A very broad scientific consensus endorses the IPCC position and agrees that solar irradiation is not the cause of climate change for two reasons [NAS1][NAS2] :
- Since the beginning of the 20th century, the average amount of solar energy received by the Earth has remained constant within 0.1 % [BLA] ;
- If the Sun were responsible for global warming, this warming would act in all layers of the atmosphere, from the surface to the upper atmosphere (stratosphere). However, the observations instead show warming at the surface and cooling in the stratosphere, which is consistent with the fact that the warming is caused by an accumulation of heat-trapping gases near the Earth's surface.

C1.3. Controversy :

Some people, called "climate skeptics", express denial of global warming and are divided into four main trends [WIK7] :
1. those who deny global warming ;
2. those who admit global warming but deny its human origin ;
3. those who admit global warming but deny its impacts ;
4. those who have no opinion on global warming but deny the scientific consensus on the topic (conspiracy theory).
The motivations are varied and lie essentially between two positions : doubt in good faith and doubt proclaimed out of interest [POI].

In the United States, in 2023, one in two inhabitants is climate skeptic [RFI] with motivations essentially oriented towards economic interest. Positions of denial, sometimes violent, are mainly held by "skeptical bloggers", supporters of conservative economic policies, industrialists opposed to the taxation of CO2 emissions and some groups financed by the tobacco and fossil fuel industries [ WIK7][RFI].
In the "top 3" of the most climate-sceptical countries, we find Saudi Arabia at the top, then come the United States and Australia, these countries being also three major producers of hydrocarbons (oil, gas and coal) [RFI].

In France, in 2022, 37 % of people consider themselves climate skeptics, including 8 % belonging to trend no. 1 [FJJ]. We can cite :

• Perplexity : some people doubt in good faith, often through ignorance of the facts or on the contrary by "drowning" in the multitude of facts.
• Invisibility : Unlike the weather, climate change is almost invisible because it occurs over very long periods of time. For people who have not suffered a major climatic disaster (hurricane, flood, etc.), denial is natural [MDS].
• Incongruity : for some people, mainly from the working classes, the "end of the month" often supplants the "end of the world" [ZEK].
• Disinformation : for some people, especially young people, social networks are the main, or even only, source of information [HIL]. Their algorithms are designed to favor content that generates the most emotions, or even the most toxicity or insults, which is particularly the case with climate skeptic discourse [LAP][FRI].
• Social conformism : In some communities where climate skepticism is the norm, people may adopt this stance to align with their social environment.
  
• Distrust : some people do not have confidence in intellectual elites (leaders, politicians, scientists, media, etc.).
• Intellectual avarice : for some people, denial makes them prefer information - even rare and controversial - that confirms their prejudice, rather than laborious analysis of the body of knowledge available on a topic [MDS]. They prefer to move towards what seems simple and accessible to them, even pseudo-scientific, rather than towards complex or scientific presentations [RIV].
• Intellectual dissonance : for some people, faced with information that contradicts their beliefs, maintaining the balance of their belief system is more vital than fighting climate change [ALL][RIV].
• Fear of truth : for some people, the prospect of an inevitable and final change in the climate is intolerable and therefore simply denied [MDS].
• Fear of losing : for others, denial is a safe haven, a form of protective instinct that allows you to preserve a way of life that you refuse to lose in today's consumer society [REP2].
• Fear of being nothing : for still others, denial is a way to assert one's social or political identity with the desire to be heard, listened to, recognized, admired, which can turn into "Mr. I know everything".
• Fear of conflict : for some people who have difficulty listening, denial is a reaction aimed not at dominating, but at avoiding being crushed, which can turn into "Mr. I am always right".
• Fear which hides others : the prospect of climate change relays other threats in large number (nuclear, atomic bomb, AIDS, mad cow, flood, etc.) which, instead of arousing generalized and lasting fear, end up fading after each media scoop. By crying wolf, no one believes it anymore. [MDS].

The controversy is therefore not scientific but societal [AFI].
When the doubt is in good faith, the controversy is rather passive, experienced in public opinion as a possible, probable and uncertain scenario, in a word a "discreet" and silent catastrophe [MDS].
When the doubt is proclaimed out of interest, the controversy is active, often polluted with verbal violence, particularly on the X platform (formerly Twitter).

C1.4. Greenhouse gas :

The Earth constantly receives energy from the sun in the form of visible light. 30 % is reflected by the atmosphere and the earth's surface, 20 % is absorbed by ozone and water vapor in the atmosphere, 50 % is absorbed by the earth's surface which heats up and emits infrared radiation from all the more intense as the surfaces are hot.
10 % of this radiation is emitted towards the universe, 90 % is absorbed by some gases called "greenhouse gases" and partly reradiated towards the surface, thereby slowing the loss of heat into space and causing global warming.
The Earth thus maintains an average temperature of +15 °C by a natural balance between the energy of the sun absorbed and that re-emitted in the form of infrared radiation. Without these gases, the average temperature on Earth would be -18 °C, and life as we know it would become impossible [NAS1][MTE1][DUF][WIK2][WIK3].
Since the beginning of the 20th century, man has considerably increased the quantity of greenhouse gases naturally present in the atmosphere, thus modifying the climatic balance through an additional greenhouse effect [MTE1].

These gases are essentially made up of the following elements [NAS1][WIK1][DUF][CDE][FRA1][ADT][CAR][BEN] :

• Water vapor (H2O), contained in the atmosphere and in the clouds, and contributing mainly of the natural greenhouse effect. Human activities have no direct influence on this water vapor, except on a local scale, such as near irrigated fields. Human activities, on the other hand, have an indirect influence via global warming which reinforces the global greenhouse effect by accentuating the evaporation of water (7 % more humidity per additional degree Celsius [GIE]).
• Carbon dioxide (CO2), released by natural processes (such as volcanic eruptions) and by human activities. It contributes 65 % to the additional greenhouse effect, mainly due to fossil fuels (60 % : extraction and combustion of coal, oil and natural gas) and deforestation (30 % : fewer trees to absorb CO2 through photosynthesis).
• Atmospheric methane (CH4), released by natural processes (such as the fermentation of plant matter in wetlands) and by human activities. It contributes 15 % to the additional greenhouse effect, mainly due to fossil fuels (30 % : leaks during production and transport of oil and natural gas), agriculture (40 % : gastric fermentation of ruminants, spreading of slurry, rice cultivation) and to municipal landfills (20 %).
• Nitrous oxide (N2O), released by natural processes (such as the decomposition of plants at their life end) and by human activities. It contributes 5 % to the additional greenhouse effect, mainly due to agriculture (spreading of nitrates of mineral origin (nitrogen fertilizers) and organic (slurry and manure)).
• Tropospheric ozone (O3), released by chemical reaction between carbon compounds including methane and nitrous oxide, therefore indirectly by natural processes and by human activities. It contributes 10 % to the additional greenhouse effect.
• Chlorofluorocarbons (CFCs), released exclusively by human activities (pesticides, cosmetics, aerosols, etc.). They contribute 5 % to the additional greenhouse effect and are the cause of the "hole" in the stratospheric (at high altitudes) ozone layer. They have been banned since 1987 via the Montreal Protocol. Substitute products (HFCs) are not harmful, but contribute just as much to the additional greenhouse effect.

In summary, according to these figures, global warming of human origin (additional greenhouse effect) is mainly due to fossil fuels (47 %), agriculture (25 %) and deforestation (20 %).

In France, the transport sector constitutes the largest source of greenhouse gas emissions, accounting for 30 % of national emissions.
Over the entire life cycle of vehicles (extraction and processing of raw materials, manufacturing, transportation and use of the vehicle), these emissions are attributable as follows : passenger cars (53 %), heavy goods vehicles (27 %), utility vehicles light (15 %), air transport (3 %) and other modes of transport (2 % : two-wheelers, rail and maritime) [GRE].

C1.5. Carbon footprint :

The carbon footprint (or GHG balance) of a product, a person, a company, a sector of activity or a territory is a measure of the cumulative quantity of all greenhouse gas emissions that can be attributed to it. This measure can be evaluated according to two conventions :
    - either in direct emissions due to the use of energy by the final consumer ;
    - either in life cycle analysis taking into account emissions due to the use of energy but also indirect emissions due to all upstream energy transformations (research and development, production, transport, distribution ), or even downstream (recycling, dismantling) [WIK4].
Example of carbon footprint for different modes of transport (in CO2 equivalent per passenger over 100 km) : plane (20 kg), motorcycle (19 kg), gasoline car (15 kg), diesel car (14 kg), electric car (10 kg), coach (3 kg), TGV (0.2 kg) [SEL].
For a greenhouse gas, its contribution to the greenhouse effect is measured by its Global Warming Potential (GWP) defined as the radiative forcing (i.e. the radiative power that the gas returns to the ground), accumulated over a reference period of 100 years and measured relative to the same mass of CO2.
The GWP is 1 for CO2 ; 8 for water vapor ; 30 for CH4 ; 300 for N2O ; 700 to 15,000 for CFC, HFC and PFC ; 17,000 for the NF3 ; 25,000 for SF6.
The carbon footprint of gas is then expressed in grams of CO2 equivalent per kilowatt-hour (gCO2eq/kWh) corresponding to the product of the mass of gas (mog) by its Global Warming Potential (GWP).
The carbon footprint of gas is sometimes also expressed by a Carbon Equivalent (CE) which only measures the mass of carbon (C) contained in the CO2 emitted. We then have the relationship : CE = 0.2727 x mog x PRG

The Bilan Carbone is a method of calculating the carbon footprint according to three distinct scopes of emissions (direct induced by the combustion of fossil fuels, indirect induced by energy consumption, indirect other).
It takes into account the six greenhouse gases designated by the Kyoto Protocol (CO2, CH4, N2O, hydrofluorocarbons (HFC), perfluorocarbons (PFC) and sulfur hexafluoride (SF6)), as well as trifluoride nitrogen (NF3), and water vapor in the case of air transport [WIK5].

The ecological footprint (or environmental footprint) covers a broader spectrum and consists of estimating the quantity of land and water necessary for an individual or population to meet its needs without depleting natural resources or disrupting the ecosystem.
More than half of the French ecological footprint is due to the carbon footprint [WIK6].

C1.6. Impacts :

The main effect of global warming is [NAT1] :

• to evaporate more water contained in the oceans and soils, which makes the air globally warmer and more humid, leading to an increase in storms and heavy rains but also, paradoxically, more intense periods of drought [NAT2].
  In Metropolitan France, since 1961, there has been :
      - an increase in the number of hot days (5 days of summer temperature (T > 25 °C) per decade) [MEF1][BLA] ;
      - a decrease in the number days with frost (4 days per decade) [BLA] ;
      - a decrease in the number days with snowy ground (7 days per decade) [MEF1][BLA] ;
      - a great stability in the average annual cumulative precipitation (935 mm/year) but with regional disparities : significant increase in the northern half (particularly the North-East), significant decrease in the southern half (particularly the South-East and the Mediterranean rim) [MEF1][SEN] ;
      - an increase in the intensity and frequency of heavy daily rains on the Mediterranean rim [MEF1][ONE] ;
      - an increase in the intensity of storms associated with a decrease in their frequency, in the Mediterranean regions [MEF2].
  Warning : Some articles on the Internet present different figures or reverse disparities, and without citing their sources.
• to warm the water contained in the oceans and glaciers, which leads to a rise in sea level due to the thermal expansion of waters and the melting of mountain glaciers and polar ice caps. Since the beginning of the 20th century, ocean water has been rising at a rate of approximately 2 mm per year (and 4 mm per year over the last decade) [WIK8][MTE2].
• to warm urban buildings whose heat is reflected in the basements, causing the contraction of some materials, such as soft clay, and the expansion of others, such as limestone. As urban basements heat up more and more, they are deformed, even cracked, and affect the sustainability of city infrastructures [REP].
• to warm frozen soils. The Far North will particularly suffer from warming : all infrastructure is based on frozen, and therefore rigid, soil, the melting of which will completely destroy its cohesion. We are already seeing collapses of infrastructure and homes [POI].
• to displace populations by exposing them to a risk of poverty, rain floods which can wash away shanty towns, heat which can make it difficult to work in the open air, and lack of water which can harm crops [NAT1].

By the end of the century, if GHG emissions follow their current trajectory without additional climate policy and with high population growth (IPCC SSP3-7.0 scenario), warming will be +4 °C with sea levels rising 1 m relative to the pre-industrial reference (1850-1900) [MTE4].
In this probable scenario, particularly if States engage in regional or global conflicts to the detriment of international climate policies, the IPCC identifies several key risks for Europe, which directly concern France [RCA1] :

• Heat waves : the number of people who will die from heat will reach 5000 per year in France (compared to 1500 currently). Heat waves will also have irreversible consequences on ecosystems, particularly on Mediterranean biodiversity : disappearance of plants and species, destruction of sea meadows [RCA1].
• Decreases in agricultural yield : a direct consequence of the previous risk, but also of drought and rainfall variability, crop losses will continue to increase, endangering the livelihoods of producers [RCA1].
• Water shortages : over the past 20 years, land water storage has decreased by one centimeter per year [NAT2]. This agricultural and hydrological drought is mainly due to the more rapid evaporation of water present in the soil and the evacuation of surface water during heavy rains before it has time to fill the groundwater tables [FRA2].
  Added to this is water pollution, particularly at the agricultural level by excess nitrates and pesticides, which compromises the quantity and quality of available water [IDV][BEN].
  Added to this are our increasingly water-intensive consumption patterns at the industrial and domestic level [AMB].
  The risk of Water shortages particularly concerns the south of France, with more than a third of the population in this area potentially lacking water during part of the year [RCA1].
• Coastal flooding : France is one of the European countries most threatened by coastal flooding [RCA1], in particular the Mediterranean coast where many cities, heritage sites and natural wetlands are very close to the coast.
• Desertification : erosion of the surface layer of soil affects cultivated land and natural environments. It is due to difficult climatic conditions (low rainfall, strong winds, excessive heat, etc.) and fragile soils (thin or sandy soils), as well as inappropriate human activities such as arson, overgrazing, overexploitation agricultural soils, deforestation, unsuitable irrigation practices, excessive soil concreting, etc. [LAR].
  Europe is increasingly affected by desertification due to human activities [CCE]. Forests around the Mediterranean, including southeastern France, could disappear in favor of semi-desert areas like the steppes [ROY].
• Particular impacts in Overseas Territories : extreme events (heat waves, cyclones, etc.) will be more and more frequent and intense. Rising water levels will seriously threaten habitats. Ecosystems will also be in great danger with coral dieback [RCA1].

C1.7. Solutions :

The fight against climate change relies on two levers :

• Reduce greenhouse gas emissions to contain global warming. The international community has set itself the objective of limiting the rise in temperatures to 2 °C : this is mitigation [MTE2].
• Adapting society to the impacts of global warming : this is adaptation [MTE2]. In Europe, despite the need to act immediately, adaptation is very insufficient. The obstacles cited by the IPCC include a lack of political will, weak commitment from citizens and the private sector as well as a "weak sense of urgency" [RCA1].

The recommended solutions are as follows [RCA2] [MTE2][MTE3] :

• Energy : get out of fossil fuels and invest in renewable energies, particularly solar and wind energy.
• Sobriety : move towards a deconsumption society by reducing energy demand, but also for materials, land, water, etc., while ensuring the well-being of people. Examples of actions for a more sober society :
      - Give priority to car-free mobility, favoring walking and cycling for example;
      - Favor public transport;
      - Promote electric vehicles;
      - Reduce air travel (especially long-haul flights).
• Adaptation : deploy measures to adapt to changes already underway and anticipate those to come. For example, diversifying agricultural crops, greening cities to cope with heat waves, developing alternative activities to alpine skiing in mountain resorts.
• International cooperation in finance and technology.

C1.8. Sources relating to climat change :

[ADT] Académie des technologies, Le méthane - d'où vient-il et quel est son impact sur le climat ?.
[AFI] Afis Science, Le "climato-scepticisme" : un concept fourre-tout.
[ALL] Vanessa Allnutt, Les climatosceptiques contre la science.
[AMB] Valentine Ambert, Va-t-on manquer d'eau ?, Youmatter.
[BEN] Marc Benoît, Pollutions agricoles, CNRS Editions.
[BLA] Guillaume Blanc, Le réchauffement climatique.
[CAR] Carbone4, L'ozone des basses altitudes, une épée à double tranchant.
[CCE] Cour des Comptes Européenne, Lutte contre la désertification dans l'UE : le phénomène s'aggravant, de nouvelles mesures s'imposent.
[CDE] CDE - Connaissance des Energies, Gaz à effet de serre : d'où proviennent les émissions de méthane ?.
[DEL] Céline Deluzarche, Pourquoi manque-t-on de plus en plus d'eau alors que les pluies augmentent ?, Futura.
[DUF] Jean-Louis Dufresne, L'effet de serre, Planet Terre.
[FJJ] Fondation Jean Jaurès, Climatoscepticisme : Le nouvel horizon du populisme français.
[FRA1] Franceinfo, COP26 : on vous explique ce qu'est le méthane, l'autre gaz à effet de serre qui réchauffe le climat.
[FRA2] Franceinfo, Changement climatique : on vous explique pourquoi sécheresse et inondations sont parfois liées.
[FRI] France Inter, Algorithmes : les meilleurs amis des climatosceptiques.
[GIE] GIEC, Synthèse du rapport AR6 du GIEC publié le 27/03/2023.
[GRE] Greenly, Les transports, premier secteur émetteur en France.
[HIL] David Hiler, Réchauffement climatique : comprendre ceux qui n'y croient pas, Le Temps.
[IDV] idverde, Comment réduire les risques de pénurie d'eau ?.
[LAP] Pascal Lapointe, Les réseaux sociaux favorisent le discours climatosceptique ? Vrai, Agence Science-Presse.
[LAR] Larousse, Désertification.
[MDS] Martin de La Soudière, Le changement climatique, une "grande peur" collective ?.
[MEF1] Meteo France, Climat HD.
[MEF2] Meteo France, Tempêtes en France métropolitaine.
[MTE1] Ministère de la transition écologique et de la cohésion des territoires, Pourquoi la Terre chauffe ? 14 septembre 2018.
[MTE2] Ministère de la transition écologique et de la cohésion des territoires, Dossier de presse - 1er Plan national d'adaptation au changement climatique, 20 juillet 2011.
[MTE3] Ministère de la transition écologique et de la cohésion des territoires, Observations du changement climatique.
[MTE4] Chiffres clés du climat - France, Europe et Monde (décembre 2022).
[NAS1] NASA, Les causes du changement climatique.
[NAS2] NASA, Le Soleil est-il à l'origine du réchauffement climatique ?.
[NAT1] Nations Unis, Causes du changement climatique.
[NAT2] Nations Unis, L'eau - au coeur de la crise climatique.
[ONE] ONERC, Les évènements météorologiques extrêmes dans un contexte de changement climatique.
[POI] Jean Poitou, Climat : distinguer le vrai du faux, Progressistes.
[RCA1] Réseau Climat Action France, 6e rapport du GIEC : quelles sont les conséquences réelles du changement climatique ? 28-02-2022.
[RCA2] Réseau Climat Action France, Synthèse du 6e rapport du GIEC : l'urgence climatique est là, les solutions aussi, 20-03-2023.
[RCA3] Réseau Climat Action France, 6e rapport du GIEC : quelles solutions face au changement climatique ? 04-04-2022.
[REP1] Reporterre, Le réchauffement des sous-sols, une "menace silencieuse".
[REP2] Reporterre, Déni de réalité : pourquoi le climatoscepticisme progresse.
[RFI] RFI, Pourquoi y a-t-il encore autant de climatosceptiques aux Etats-Unis et dans le monde ?.
[RIV] Johan Rivalland, La Démocratie des crédules - Critique du dernier livre de Gérald Bronner.
[ROY] Florentin Roy, Les forêts en Méditerranée vont-elles disparaître ?, Youmatter.
[SEL] Selectra, Empreinte Carbone : calcul, définition et conseils de réduction.
[SEN] Sénat, Adapter la France aux dérèglements climatiques à l'horizon 2050 : urgence déclarée.
[TSP] The Shift Project, Climat : synthèse vulgarisée du 6ème rapport du GIEC (mars 2023).
[WIK1] Wikipedia, Gaz à effet de serre.
[WIK2] Wikipedia, Effet de serre.
[WIK3] Wikipedia, Changement climatique.
[WIK4] Wikipedia, Empreinte carbone.
[WIK5] Wikipedia, Bilan carbone.
[WIK6] Wikipedia, Empreinte écologique.
[WIK7] Wikipedia, Déni du réchauffement climatique.
[WIK8] Wikipedia, Elévation du niveau de la mer.
[ZEK] Marie Zekri, 37 % des Français se considèrent climato-sceptiques, National Geographic.

C2. Footprints of mammals and birds

Footprints printed on the ground or in the snow allow most mammals and birds to be identified.
For birds, the identification method is based on each Isolated footprint, a bird being able to only walk or hop on the ground.
For mammals, the identification relies on the joint use of three different methods based on the following observations :
- Isolated footprint,
- Succession of footprints, giving the movement pattern of the animal,
- Droopings of the animal.

1. Isolated footprint
2. Succession of footprints
3. Droppings

   

C2.1. Isolated footprint

Mammal footprints are all Hand type (with 3, 4 or 5 fingers per paw, excluding palm), Pads type (with 4 or 5 digital pads per paw, excluding palm) or Hooves type (with 1, 2, 3 or 4 fingers per paw, excluding foot sole).
Bird footprints are all Hand type comprising, with some exceptions, 3 fingers per paw supplemented by a fourth opposite finger (thumb) which may be reduced or completely absent.
The 4 slides below present a method of identifying mammals and birds from their isolated footprints.

Sources :
(empreintes des mammifères) Ma Chasse, Les mammifères.
(empreintes des mammifères) France Nature Environnement - Haute-Savoie, Les empreintes.
(empreintes des mammifères) Gilles Christophe, FRAPNA, Les mammifères de Rhône-Alpes- les empreintes.
(empreintes des mammifères) Salamandre, Empreinte de mammifères.
(empreintes des oiseaux) Ma Chasse, Les oiseaux.
(oiseaux) Zadi Bridge, Combien les oiseaux ont-ils de doigts ?.
(ongulés) Puverel Camille, Leprince Julie, Atlas des mammifères de Rhône-Alpes - Les ongulés.

C2.2. Succession of footprints

The slide below presents a method of identifying quadrupedal mammals from their movement pattern.
The legs are marked as follows : 1 left front leg, 2 right front leg, 3 left hind leg, 4 right hind leg, P projection in the air (hanging time).
The main movement patterns are as follows :

• Walk : 4-stroke movement which responds to a double principle : the movement of a front leg is followed by that of the hind leg located diagonally ; the movement of a hind leg is followed by that of the front leg located on the same side. The walker therefore advances the left front leg (n°1), then the right hind leg (n°4) which is printed just behind or on the trace of the front paw, then the right front leg (n°2), then the left hind leg (n°3). The formula for displacement is : 1 4 2 3 (see photo below and slide below).
  
• Trot : 2-stoke movement, each followed by a projection. Apart from the addition of the two projections, trotting is almost identical to walking, the crossed movement of the front leg and the hind leg no longer being successive but simultaneous. The formula for displacement is : 14 P 23 P (see photo below and slide below).
  
• Back up : 2-stroke retrograde movement. Backing up is walking backwards using diagonal strides, which is almost identical to trotting without the two projections. The displacement formula is : 14 23 (see photo below of Blog Equitation Nord, and slide below).
       
• Amble : 2-step movement, each followed by a projection when the movement is fast. The ambler swings its body from left to right, moving its legs together on the same side. The hind paw prints next to the trace of the front paw. Apart from the addition of the two possible projections, ambling is almost identical to walking, the movement on the same side of the hind leg and the front leg no longer being successive but simultaneous. The formula for displacement is : 31 (P) 42 (P) (see photo below and slide below).
  
• Gallop (left or right) : 3-step movement with additional time of hanging. The galloper advances the hind leg first, then together the two diagonal legs which are not part of it, then the front leg diagonally opposite to the one which landed first, then throws itself into the air. Apart from the addition of the projection, galloping is almost identical to walking, the movement of these two diagonal legs no longer being successive but simultaneous. The formula for displacement is (see slide below) : 4 23 1 P for a gallop left (see photo n°1 below) and 3 14 2 P for a gallop right (see photo n°2 below).
  
  
• Grouped leap : 2-step movement with additional time of hanging. The leaper has hind legs that are generally larger than the front legs. Just after the leap, the leaper places its front paws together on the ground, then its hind paws which are printed on the front paws tracks, then leaps into the air. The formula for displacement is : 12 34 P (see photos below from video Youtube "CHEVREUIL", and slide below).
     
• Ungrouped leap : 2-step movement with additional time of hanging. The leaper has an elongated body with generally short legs. Just after the leap, the leaper places its front paws on the ground (together for the squirrel or one in front of the other for the hare), then passes its hind paws on each side of the body which are printed in front of the front paws tracks, then leaps into the air. The formula for displacement is : 12 34 P or 1 2 34 P (see photos below from Pilon Michel, and slide below).
     
  

Nota :
- Walking exists in all quadrupedal mammals. For some, it is sometimes slow and infrequent (that of the squirrel for example).
- For the first five movement patterns (Walk, Trot, Back up, Amble, Gallop), the order of legs movement is always the same : 1 4 2 3, with some legs sometimes being moved together, being part of the same diagonal or the same side.

Sources :
(amble) Wikipedia, Amble.
(amble et galop du cheval) Dictionnaire visuel - Allures du cheval.
(bond du renard, lièvre et écureuil) Espaces, Suivre à la trace.
(bond de la belette) J'ai suivi une petite belette sauvage (Youtube, 5:45).
(bond de l'écureuil) Pilon Michel, Forum Image et Nature.
(démarche des mammifères) Les Chasseurs à l'Arc de la Réunion, LES TRACES D'ANIMAUX DANS LA FORET (EUROPE).
(démarche des mammifères) Couzi Laurent, Planche N°1 intitulée "Empreintes animales" du livre Phénomènes, Juzeau C. , Rébulard M., Caradec C., Editions du Chêne, 2023.
(marche, amble et bonds) La Presse+, Jouer au détective dans la neige.
(marche, amble et bonds) Fédération Canadienne de la Faune, A la découverte du monde du pistage d'animaux.
(pas, trot et galop du cheval) Le Monde des Chevaux, Les allures.
(pas, trot et galop du cheval) Wikipedia, Allure (équitation).
(pas, trot et galop du cheval) Lenoble du Teil Jules, Etude sur la locomotion du cheval et des quadrupèdes en général, 1873, LENOBLE_ETUDE_SUR_LA_LOCOMOTION_1873.pdf (accompagné d'un atlas de 23 planches).
(reculer du cheval) Blog Equitation Nord, Hippologie : les allures.
(reculer du cheval) Devos Emma, chevalogie.free.fr, Le reculer.
(vidéos du cheval) Hippologie.fr, Les allures du cheval.
(vidéo du trot du cerf) Cerf qui court et au trot (Youtube, 4:11).
(vidéo du galop du cheval) galop au ralenti (Youtube, 1:08).
(vidéo du galop du chameau) Course de chameaux en Egypte (Youtube, 1:54).
(vidéo du bond du chevreuil) CHEVREUIL/Sauts et Course ! BRUITX (Youtube, 2:00).

C2.3. Droppings

The slide below presents a method of identifying mammals from the shape and texture of their droppings.
Size is another clue. It is generally proportional to the length of the animal's rectum, therefore also to the size of the animal.
Color is also another clue, but it depends on the freshness of the deposit and the ingestion of some foods. For examples :
- Fresh mouse droppings are black and turn brown after about 24 hours.
- The color of hedgehog droppings can vary from black to brown to different shades of gray, depending on its diet which mainly consists of insects, molluscs and small vertebrates.
- A dog that eats too many bones or industrial food containing too much animal flour will produce white droppings. In the sun, the white color will be even more pronounced because the water contained in the droppings evaporates, bringing out the calcium.
- A wolf that swallows the bones of its prey will produce white droppings.

The deposit of droppings is generally done on the paths taken by the animal. For carnivores, in addition to the natural evacuation function, the deposit corresponds to the visual and odorous marking of the territory, often at crossroads between paths.

Sources :
(détail) Gilles Christophe, FRAPNA, Les mammifères de Rhône-Alpes - Les fèces.
(détail) Martin Alexis, Petit guide illustré des crottes de mammifères.
(détail) Salamandre, Crottes de mammifères.
(général) Espace pour la vie Montréal, Des crottes qui en ont long à dire.
(images) Lahaye Romain, Atlas préliminaire des Mammifères sauvages de Bourgogne.
(tableau) France Nature Environnement - Haute-Savoie, Les crottes.
(tableau) Carbala, Espace outil pédagogique.

C3. Planetary motion

The planetary motion is directly derived from Newton's law of universal gravitation, which governs the behavior of a system of two bodies in gravitational interaction.
Formulation : Two point bodies M and m separated by a distance d between their centers attract each other with a force F whose intensity is given by the formula :
(R1) F = G M m / d²
where G is the universal gravitational constant (G = 6.67408 10^-11 kg^-1.m³.s^-2).
This force is attractive and acts along the straight line connecting the centers of the two bodies.

In the case of an isolated system, the law of universal gravitation induces the following laws, called "corrected Kepler's laws", which may be slightly disturbed in a real context by gravitational interactions with other bodies.

1. Galilean reference frame
2. Flatness of trajectories
3. Elliptical orbits
4. Area law
5. Period law
6. Conservation of mechanical energy
7. Sources

Figures 1 and 2 : Motion of two bodies A and B of very different masses (Figure 1) and of the same mass (Figure 2) under the gravitation effect [SES].
Figure 3 : Link between trajectories (ellipse A/C, ellipse B/C, relative ellipses A/B and B/A) with C = barycenter of the system and d = distance between bodies A and B

1. Galilean reference frame :

Formulation :
- We consider an isolated system of two bodies A and B in gravitational interaction (two-body problem).
- The reference frame centered at the center of mass C (barycenter) of the system is an inertial (or Galilean) reference frame.

2. Flatness of trajectories :

Formulation : The trajectories of the two bodies are located in the same orbital plane, perpendicular to the kinetic momentum vector of the system of the two bodies, calculated relative to the barycenter of the system.
Associated Kepler's law : The orbits of the planets are planar.

3. Elliptical orbits :

Formulation :
- Each body in the system describes an elliptical orbit with one focus being the barycenter of the two-body system.
- In the case of the Sun-planet system, since the Sun is much more massive, the barycenter is very close to the center of the Sun. Consequently, the planet appears to orbit the Sun when in reality the Sun also describes a small ellipse around this barycenter (see Figure 1 above).
- This small ellipse can become significant in systems where the mass difference is less important such as in a binary star system (see Figure 2 above).
- The semi-major axes of each ellipse are aligned. Thus, when one of the bodies reaches its pericenter (the point of the orbit closest to the focus), the other body is also at its pericenter.
Associated Kepler's law : The planets describe elliptical orbits with the Sun at one of the foci.
Elliptical orbit equation (in polar coordinates) : r = p/(1 + e cos[θ])
with :
   θ r = distance from the body to the occupied focus of the ellipse
   p = focal parameter
   e = eccentricity
   θ = polar angle
We have the relations :
(R29)
a = p/(1 - e²)
b = p/(1 - e²)^1/2
c = (a² - b²)^1/2 = e a
b² = a²(1 - e²)
p = b²/a
S = π a b
with :
   a = semi-major axis
   b = semi-minor axis
   c = semi-focal distance (or distance between the ellipse center and one of the foci)
   S = area

4. Area law :

Formulation : The radius vector connecting a body to the occupied focus of the ellipse sweeps out equal areas in equal times.
Associated Kepler's law : The radius vector connecting the Sun to a planet sweeps out equal areas in equal times.
Expression of the area law : dS/dt = (1/2) r² dθ/dt = constant = (1/2) σ/m
with :
   S = area swept out by the radius vector in the orbital plane
   r = distance of the body from the occupied focus of the ellipse
   θ = polar angle
   t = time
   σ = angular momentum of the body relative to the occupied focus
   m = mass of the body

5. Period law :

Formulation : The orbital period of each body is given by the formula :
(R70) T²/a³ = 4 π² / k
with :
   T = orbital period
   a = semi-major axis of the ellipse
   m and M = respective masses of bodies A and B
   Case of body A rotating around body B : k = k_A/B = G (m + M)
   Case of body A rotating around the barycenter C of the system : k = k_A = G (M³ / (m + M)²)
   Case of body B rotating around the barycenter C of the system : k = k_B = G (m³ / (M + m)²)
Associated Kepler's law : The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
Invariance of orbital period : Given the relation (R89), T depends only on the mechanical energy E_mec of the system.

5. Conservation of mechanical energy :

Formulation : The mechanical energy of the system, the sum of the kinetic energy of the relative motion between bodies and the potential energy of interaction, is conserved over time.
Expression of the mechanical energy E_mec as a function of the parameters p and e of the ellipse :
(R80) E_mec = (1/2) (G m M / p) (e² - 1)
with :
   m and M = respective masses of bodies A and B
   p = focal parameter of the relative ellipse in the motion of A relative to B, or of B relative to A
   p = p_A/B = p_B/A = p_A/C (1 + m_A/m_B) = p_A/C + p_B/C
   e = eccentricity of the ellipse
This energy is always negative for an ellipse (|e| < 1).

6. Sources relating to planetary motion :

[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[CHE] Jonathan Chenal, Introduction à l'astronomie de position
[FEM1] FEMTO - Mécanique, Problème à deux corps
[FEM2] FEMTO - Mécanique, Forces centrales
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
[PST] Gravitation : le problème des deux corps avec PSTricks - partie 1
[SES] SESP, Mouvement de deux corps sous l'effet de la gravitation
[SOR] Joël Sornette, Le problème à deux corps - Mouvements à force centrale
[VIE] Alain Vienne, Eléments d'astronomie fondamentale

D. Applied sciences and technologies

D1. Scientific approach and systemic modeling

1. Scientific approach
2. Systemic modeling

D1.1. Scientific approach :

The scientific approach consists mainly of six steps :
    1. Observation and measurement of a phenomenon ;
    2. Systemic modeling and formulation of the simplest theory correctly accounting for all the observed facts ;
    3. Experimentation and validation of the theory ;
    4. Comparison with existing theories ;
    5. Communication of results for peer review and possible criticism ;
    6. Use of the theory to predict or reproduce the phenomenon.
Warning : Any criticism must be constructive to be admissible, that is to say be factual, without value judgment and without ironic or disrespectful remarks, in short, be worthy of the critic.

D1.2. Systemic modeling :

The systemic modeling is a stage of the scientific approach which consists in describing physical phenomena in the form of systems. The challenge is to find the right level of model : neither too simple to take into account all the physical observations, nor too complex to set the model parameters from these observations.
Systemic modeling also aims to divide systems into subsystems in an optimal way according to four main principles of systemes urban planning :

1. "Divide to conquer" or modularity principle. The goal is to cut the system into subsystems of optimal size and each having its autonomy of exploitation and use.
The temporary unavailability of a subsystem does not prevent the other subsystems from operating.

2. "Group to simplify" or subsidiarity principle. The goal is to pool what can be pooled and to treat each specificity as a differential relative to the general case.
Complexity is isolated in easily manageable special case subsystems and does not put generic subsystems at risk.

3. "Distribute to better communicate" or reducing adhesions principle. The goal is to minimize the adhesions between subsystems and to compensate by a dynamic cooperation between them.
The data exchanged between subsystems are only created and modified in a single subsystem (notion of proprietary subsystem).
The information exchanges between subsystems are done via standardized interfaces.

4. "Start small but think big" or progressiveness principle. The goal is to provide for an evolution of the system in stages and starting from the existing one.

D2. Digital optical disk (CD, DVD and BD)

1. Definition
2. Constitution
3. Lifetime
4. Choice of media
5. Use
6. Conservation
7. Sources

D2.1. Definition :

The Digital Optical Disk (DON) is a removable flat disk used to store digital data in the fields of computers, audio and video.
The best known disks are CD, DVD and BD :

• CD (Compact Disk) is used to store all types of digital data with reduced storage capacity (approximately 700 MB). Its reading system is an infrared laser whose wavelength is 780 nm, which does not allow reading DVD and BD.
• DVD (Digital Versatile Disk) can also store any type of digital data with a large storage capacity (4.7 GB on average). Its reading system is a shorter wave infrared laser (650 nm). The often-used term "Digital Video Disk" is a misnomer because the stored data may also be non-video.
• BD (Blu-ray Disk) can store high-definition video data (from 7 GB to 128 GB). Its reading system is a blue-violet laser with an even shorter wave (405 nm), which makes it possible to read video DVD and audio CD.

The acronym CD, DVD or BD is followed by the burning mode : ROM (Read-Only Memory) for read-only disk, ±R (Recordable) for disk that can only be written to once, ±RW (Rewritable) or ±RE for rewritable disk.
The acronym ± of burning mode corresponds to two different DVD standards, the old players not being compatible with the + standard which is more recent.

D2.2. Constitution :

A digital optical disk is a stack of several layers (see Figure above) :

• Base layer in transparent plastic material (polycarbonate) ;
• Organic dye layer (only for ±R disks) ;
• Reflective metallic layer which reflects the laser beam towards the photosensor of the laser head ;
• Protective layer (anti-UV varnish) which protects the reflective layer ;
• Polymer layer supporting the printed information.

Data is written in the base layer for ROM, in the dye layer for ±R and in the reflective layer for ±RW, on a spiral-shaped track that is almost 5 km long for disks CD, from the center outwards.
Optical reading is binary (0 or 1). The information is made up of micro-pits and lands. Any state change (land to micro-pit or vice versa) is translated by a '1', and all the lengths of lands and micro-pits by '0'.

D2.3. Lifetime :

The objective lifetime of a digital optical disk ranges from 2 years to 20 years, and sometimes longer if all precautions are taken. It strongly depends on the choice of media, the use conditions and the storage conditions of the disk.

D2.4. Choice of media :

• Quality : choose a major brand disk rather than a generic disk.
• Origin : avoid buying at train stations or markets or fairs, as disks as discs can stay in damp or direct sunlight for days on end. Beware of batches of 50 or 100 DVD which are sold without a protective case.
• Wear by mechanical contact : no possible wear because the reading head is never in contact with the disk.
• Aging or corrosion : prefer ±R disks over others. The main factor that determines the lifetime of a disk is indeed the reflective layer which is generally gold or silver for ±R disks and aluminum for the others (therefore more fragile to corrosion).

D2.5. Use :

• Handling : take the disk by placing one finger in the center and another on the edge. Do not touch the engraved part below and above (the fingers sweat being acidic). Do not put the disk anywhere. If the protective layer is scratched, the cracks allow air to pass through which oxidizes the reflective layer.
• Storage : place the disk upright in its case, the printed side upwards.
• Cleaning : use a dry soft cloth, wiping the disk from the center of the disk outwards and never in a circle.
• Burning : do not use an aging burner. Ensure that the disk is compatible with the burner. Burn at low speed (4x or 8x) neither too slow (1x) nor too fast (52x).

D2.6. Conservation :

• Labeling : label only on the internal transparent band.
• Storage : store the disk preferably in a dry place, in the dark and at a constant temperature (between 4 °C and 25 °C). Keep the disk in its original sleeve or case, and in an upright position to avoid warping.
• Backup : make a copy every 5 years.

D2.7. Sources relating to Digital optical disk :

Wikipedia - Disque Compact.
Wikipedia - DVD.
Wikipedia - Disque Blu-ray.
Level - Quelles sont les différences entre un CD et un DVD ?.
Infobidouille - La question technique 6 : CD, DVD, BLU-RAY, RW... Comment ça marche les supports optiques ?.
FISTON production - Inquiétudes sur la durée de vie des DVD enregistrables.
Maxicours - Stockage optique.
expert multimedia - Caractéristiques techniques d'un DVD.
Chaumette O., AGIR/PHYSIQUE/CHAP 20 - Le principe de la lecture d'un disque optique (CD, DVD, BluRay...).
Gouvernement du Canada - Durabilité des CD, des DVD et des disques Blu-ray inscriptibles.
Centre de conservation du Québec - Critères de choix d'un disque optique, guide d'entretien et de manipulation.
SOSORDINATEURS - Quelle est la durée de conservation des CD, DVD et Blu-Ray.
VERBATIM - Les différences significatives de performance entre les couches réfléchissantes en argent et en aluminium soulignent l'importance de savoir ce que vous achetez.
Que Choisir - Durée de vie des DVD - Conseils.
Ballajack - Durée de vie d'un CD ou DVD gravé, comment les conserver ?.

E. Human and medical sciences

E1. The life laws

A small number of truth seekers, notably Svâmi Prajnânpad, have simply described the laws of life as follows (from the book [Petit Régis, Une approche scientifique du silence]).

1. Definitions
2. Law of difference
3. Law of change
4. Law of causality
5. Law of the psyche
6. The life purpose
7. Silence and fullness
8. To love
9. To desire
10. To act
11. To live in society
12. To give
13. To help others
14. To die
15. Sources

E1.1. Definitions

* Svâmi Prajnânpad, the truth, emotion / feeling, to think / to see

Svâmi Prajnânpad (alias Svâmiji, 1891-1974) was a Bengali Brahmin who had received dual training, classical Vedantic and modern scientific trainings.
A master of wisdom and lucidity, his rigorous approach is a dive into the heart of the unconscious which reveals the difficulties hindering the silence of mental. No God, no ritual, no paradise.
André Comte-Sponville said about him : "This master is content to see, to be one with what he indifferently calls truth or reality, which is neutral, neither good nor bad, neither pleasant nor painful, and promised only change or death." [PDS 2]
According to the specific vocabulary of his teaching [EHM 1] :

• to see consists of recognizing reality as it is without distorting it ;
• to think (functioning also designated by the mental) consists in projecting onto reality what it should be according to our preferences and pleasing ourselves in this imagination ;
• the emotion corresponds to an affective state of reality refusal which accompanies the thought and causes a suffering of separation ;
• the feeling arises when we accept reality and feel oneness with it.

* Inner peace, truth, science

• Outer peace is impossible without inner peace. [GKG 2]
• The truth is the middle ground between fascination and disillusionment with the world. It is found not by seeking it but by creating peace within oneself. [Anonymous]
• What is the truth ? Which is. But this definition is not complete. This is only the first half. The second half is that there is nothing other than what is. [PDS 4]
• To know if you have actually seen or if you have only thought through your mental, there is only one criterion : Do you experience any emotion ? If so, it means that the mental has started to function. When you see, there is no emotion. [PDS 4]
• Svâmiji gave the example of the doctor who "thinks" nothing of the patient when the latter enters his office. He examines it, auscultates it, "sees" the state in which it finds itself. He has no a priori, he does not think but "sees" that is to say examines, observes, reflects, discriminates on facts. [RFD 1]
• You cannot own the truth. We can only be the truth. One must die to the life of the mind in order to be reborn to the life of truth. [PDS 4]
• Yesterday is in your memory. Tomorrow is in your dream. Today is the only reality. [Anonymous]
• Svâmiji said : "What is science ? Only the search for truth." [PSP 1]
• Svâmiji once told me that adhyatma yoga is based on four pillars : vedanta vijnana, manonasha, chitta shuddhi and vasanakshaya. Vasanakshaya means erosion of desire, chitta shuddhi purification of (unconscious) memory, manonasha destruction of mind and vedanta vijnana science of vedanta (or knowledge of the life laws). [DSA 8]

* Ego, attachment, mental, identification

• The ego is a protective shell to keep out anything foreign, new, unknown. It is a structure kind of world apprehension, devoid of flexibility and adaptability to change. [RFD 1]
• Svâmiji said : "Man's very first perception in his life, what he sees as soon as he opens his eyes, is considered by his mental as stable from the beginning. Every object exists for him. Constantly associating, he clings to it. He believes that all these things exist and will continue to exist. He does not want to accept that anything can be lost." [RFD 3]
• The ego expresses itself on different levels : its prime contractor is the mind (manas), the central organ of refusal, whose intellectual aspect is thought (citta), the affective aspect is emotion (bhâvana), the action aspect is desire (icchâ or kâma). [RFD 1]
• The mental develops from physical sensations. The principle is as follows : the form is there, the object is there; and a contact occurs with that. Touch causes sensation. From sensation comes perception. From perception comes design. And where conception comes, both pleasure and pain arise. And so we identify with them. [PSP1]
• Your mental fixations, they belong to you. They prevent you from seeing, accepting and realizing what is. Welcome them with kindness, taking care not to pursue them, not to maintain them. [Anonymous]

* Thought, emotion, desire

• Gurdjieff said that the ordinary man lives mainly in three worlds which are motor (sensations), emotional (emotions) and intellectual (thoughts). But the sage has two other worlds at his disposal : the higher emotionnal world (feeling of unity) where emotions are neutral and without opposites (pleasant/unpleasant), and the higher intellectual world (seeing things as they are) where thoughts are neutral and without opposites (for/against). [OPD 2]
• Svâmiji said : "The mental has two functions : it produces thoughts, it takes one thing for another, and it produces emotions which keep these mental images alive." [RFD 1]
• Emotion is nothing but the product or result of seeing things other than they are. [PDS 9]
• There is a thought behind every emotion. Without thought there can be no emotion. [PDS 5]
• Emotions teach you. They lead you to the truth. From the error, which you take for the truth now, you go towards the truth. [PDS 4]
• Can we have a stable emotion ? Certainly yes. It is no longer an emotion but a feeling. An emotion can never be stable. [PDS 4]
• Svâmiji said : "Desires arise from the double belief that one can obtain something from another and that one can keep it permanently. Both beliefs are false." [DSD 9]
• Desiring something else and rejecting what is are one and the same thing, and the root of all suffering. [DEA 1]

* To be

• To be is to contemplate existence in attentive tranquillity, here and now, everywhere and always. [Anonymous]
• "To be", in the traditional sense of the word, is to be free to have, free from the desire to have, free from the fear of not having. [DSA 7]
• "The behavior of a liberated man ?" He is at ease, in all circumstances. He is at home everywhere. [PDS 4]
• The path of truth has three stages. When you feel "I am alone...", you are in emotion and therefore in ordinary life. When you feel "I am loneliness", you are on the path of knowledge and duality (me and loneliness). When you feel "neither me nor loneliness", you have come to the end of the road and of non-duality : "I am nothing and nobody, I am everyone and everything". [Anonymous]

* Spirituality

• The ways of spirituality seem full of contradictions. Arnaud Desjardins answered : "So ? Everything is true but at different levels. When Swâmi Prajnânpad says 'No one lives in the world, everyone lives in his world', this is the starting shore (the usual human condition). When he says 'Not what should be, but what is', this is the crossing over (the full recognition of duality). When he says 'Swamiji does not act, an action happens', this is the end shore (the perfect non-duality)." [DSA 21]
• Spirituality is an attitude of mind. To depend only on oneself, that is spirituality. [SNR 1]
• Spiritual experience does not absolutely abolish conditioning, but by opening us up to a dimension that transcends it, it makes us internally free from it. [DAF 2]
• Spirituality is nothing but the scent of a full life. [PDS 9]
• Frédérick Leboyer said : "The spiritual life is all the miracles that begin to happen as soon as you put the interests of others before your own". [DAL 4]

E1.2. Law of difference : Every thing is different and unique

• Each person is unique, different and perfect in themselves. [SNR 1]
• Although there are an infinite number of things in the universe, it is remarkable that no two things are the same. They are different from each other. Solids differ from liquids, and both differ from gases. Grass and shrub are different from plants, vines and trees. Animals are different from birds and birds from fish. The same is true for the billions of human beings who live on this earth. Basically what you need to know, is that everything is different. "I am here", "you are there". Both are different. Since everything is different, no one can expect the other to act in a particular way. Since he is different, he can only behave differently. So we must try to understand others rather than attribute to them the qualifier of good or bad. This is how you can overcome differences and perceive the uniqueness of everything. [SNR 1]
• Svâmiji said : "Men are equal as human beings, as carriers of the same infinite potentiality but different in their expressions. No distinction can therefore be made among human beings according to the color of their skin, their sex or their beliefs etc." [RFD 1]
• The other is other. If I want to continue to live in society, I have to adapt to what the other is, to what he expects of me. Adapting does not mean being passive, but changing what can be changed, taking into account the situation and the conditions of the moment. Effective action implies knowledge and information. [RFD 1]
• Svâmiji said : "Two things are different, two people are different... Nobody sees you, everyone sees you as he wants to see you". Therefore : "no one can judge me." [RFD 1]
• Everything is different. There are no two similar bodies, no two similar spirits. To think then that another person will act according to your wishes is contrary to the order of things. [PDS 2]

E1.3. Law of change : Everything that comes goes away

• Everything that can come will go away. The truth will not come. The truth is here and now. [PDS 1]
• Ordinary experience shows that whatever comes always goes. Day breaks, stays for a while and disappears, giving way to night. The night too stays for a while and goes away, giving way to another day. Likewise sadness comes and, after a while, it fades away. Likewise joy, jealousy, anger, etc. Likewise childhood, youth, maturity, old age come and go. Also, we must not rejoice in our fortune or be sorry for our bad luck. These are temporary states, which will disappear. We will remain peaceful, calm and serene no matter what, because what happens must change. [SNR 1]
• Death is an aspect of life, and we modern Westerners have forgotten that. We contrast death and life instead of contrasting death and birth, and remembering that life is the ceaseless play of death and birth. [DSA 10]
• By changing, one thing does not become something else. The first ceases to exist and the second springs into existence. It is we who, by linking the two forms, come to think that the thing has changed. [SNR 1]

E1.4. Law of causality : For every effect there is a cause

• The protruding nail attracts the hammer. [Japanese proverb]
• Everything that comes to you or has come to you, be it a person, an incident, a situation, has come to you because it was drawn to you. In other words, whether you like it or not, you are the one who attracted it. [PDS 4]
• Svâmiji said : "The cause is never outside. The cause is inside. All emotional reactions have their roots in you and you are the only responsible for these reactions. The external world does not there is nothing to do with it. In truth, there is no external cause, everything is in the way of absorption. In daily life, any cause triggers and awakens the true internal cause. The world exists in its intrinsic, fundamental unity. It is as it is. It is neutral and only expresses itself. Only the mental seeks to make it conform to its fantasy." [RFD 1]
• Any inner emotional reaction occurs not based on external causes but based on an internal scenario that picks up the external exciting cause. [PDS 1]
• There is no accident, no miracle, no fate, only a cause and effect relationship. What may not be clear is the web of cause and effect interconnections that produce this or that particular event. In this case, even if the totality of the causes is not known, the effect is present. It is a fact. And it must be accepted as fact, until the tangle of cause and effect can be unraveled. [RFD 1]

E1.5. Law of the psyche : The mental creates a "second", the truth is "one without a second"

• In all conditions and circumstances the truth is always one without a second. The mental creates a second. [PDS 6]
• What is the truth ? Which is. But this definition is not complete. This is only the first half. The second half is that there is nothing other than what is. [PDS 4]
• Nothing is wrong. What exists at a moment is the truth of the moment. [DSD 3]
• If you want to be happy, you have to be comfortable with what happened and what is happening, that is, with what is true. In other words, we have to accept everything. There is "only one" and "not a second". But the mental does not want to accept the one reality and it creates a second in its imagination. He then compares his creation with reality and battles with it. And here is the suffering. There is a conflict between what exists and what has been created by the mental. We create a "second" and we suffer. [SNR 1]
• Svâmiji said : "The truth is there within us. There is nothing to seek outside, nothing to add, to superimpose. You simply have to remove what covers it and prevents you from being in contact with it." [DSD 1]
• Can you say "No, it didn't happen" ? No, you can't say "no". So say "yes". There is nothing in between. What is between yes and no is an illusion. [PDS 1]
• Svâmiji said : "Just accept. Accept that the other is different. Accept everything. Do you feel nervous? Accept this nervousness too, but controlling it if you are not alone, to avoid hurting others. To control does not mean to repress." [DSD 7]
• Svâmiji said : "The reaction, the emotion are in you. The more you refuse, the more what you deny takes on weight, the more the refused thing exists, increased by your judgment on it. With the judgment which is a reaction of refusal, you add a second element to what presents itself, you double its existence : its existence, plus your reaction. On the contrary, if you really see your reaction as a reaction, there will be no further reaction." [DSD 7]
• Arnaud Desjardins said : "To accept does not mean not to act, it is to accept without emotion the raw fact - what is." [LRV 1]
• When an emotion arises, let it express itself as much as possible, be with the emotion or rather, be the emotion, and it will quickly wear out. So, see why the emotion appeared. She came simply because you didn't see the facts as they are. So try to see what the real situation was and how your mental interpreted it ! [PDS 1]
• Svâmiji said : "Bars do not make a prison... It is the refusal of the bars that makes the prison !" [RFD 1]
• Not to hope but to know ; not to believe but to see. This is the path to happiness. [CSA 1]

E1.6. The life purpose

• Existence loves you. It gives you life, not because you deserve it, but because it overflows with love. [Anonymous]
• Man is not an accomplished being. Nature develops him up to a certain point then abandons him to himself, free to become aware of his destiny and to decide whether or not he wants to pursue an interior transformation through his efforts. [OPD 1]
• The ordinary man hastily draws his conclusions about life without research, effort or personal achievement. On the other hand, the overeducated man erects around him a thick wall of words which hides the true face of life. [Anonymous]
• The truth is so simple and people have become too learned. [PDS 9]
• This world is not our home. We are a passing traveler... We entered this world empty-handed and alone, and we will leave it empty-handed and alone. [GKG 1]
• ...So, why try to "have" constantly and without limit ? Nothing will be kept when we die. Isn't it wise to seek rather to "be"? [Anonymous]
• "To be", in the traditional sense of the word, is to be free to have, free from the desire to have. [DSA 7]
• Svâmiji said : "To be free is to be free from mom and dad." [DSA 10]
• We are free from the "other" when we understand what it is. For what ? Free from what ? Free from my own mental creation. [PSP1]
• What we see through thought is the world. What we see without thought is the divine. [Anonymous]
• Renunciation is an untruth. Only detachment is the truth... A ripe fruit does not leave the branch - it detaches and falls. [PDS 10]
• "The behavior of a liberated man ? ". He is comfortable in all circumstances. He is at home everywhere. [PDS 4]
• Svâmiji defined the purpose of human life as follows : "To be able to say and feel : I gave everything I wanted to give, I received everything I wanted to receive, I did everything I wanted to do". [RFD 1]
• Human is the path that leads to truth, to the divine. [Anonymous]
• Svâmiji proposed several stages : "Me only, me and the others, the others and me, the others only." [DAL 3]
• Rigorous observation of the facts on the physical and psychic planes leads to the overcoming of forms and to inner silence. [Anonymous]

E1.7. Silence and fullness

• Large buildings remain stable because part of them (their foundations) is underground. If we want to elevate ourselves, we must become humble. [ARI 1]
• The most unique experience in life is that of inner silence. [Anonymous]
• A religious spirit is silent. He doesn't ask for anything. [NIL 1]
• To use words is to communicate. To use silences is to commune. [Anonymous]
• The supernormal is the normal, but the normal in its perfection. Nothing other than the normal in its plenitude or in its perfection. [PDS 4]
• Svâmiji said : "Perfection has no degrees. There are degrees only in imperfection." [RFD 2]
• Don't look for perfection. If you see your imperfections yourself, you are perfection, without being able to boast, flatter or be proud of them. Just be what lives in you, quite simply. [Anonymous]
• Whatever we discover in ourselves, it is not a question of whether it is good or bad but whether it is or not. [PDS 6]
• When you are absolutely silent, when you are silence, then you disappear as a person and become the whole. The water drop disappears and becomes the ocean. [Anonymous]
• Svâmiji said : "When the river is lost in the ocean, when its waters no longer have any form or name, then it becomes truly great." [LRF 1]
• The truth is nothing other than the realization that "I am nothing, I am nobody ! I am therefore everyone, I am everything". [PDS 7]
• When life is lived fully in each moment for the space of an instant, it is a continuous wonder where time is a unique and unprecedented painting which is born and dies at each instant to be replaced by another painting just as fresh and new. [Anonymous]

E1.8. To love

• Human has the right to be happy and the duty to make himself happy. Starting with loving yourself so fully that the love overflows and reaches others. [Anonymous]
• To love is to understand and feel that the other is different. [PDS 4]
• To love is not to think together but to grow together. [PDS 4]
• Love can only exist between equals. If one feels superior or inferior, it is pity, sympathy, admiration, etc. but it is not love. [PDS 4]
• Judging is not for man. What is for man is to see, to understand and to feel. And inevitably love. [PDS 9]
• Man should not try to be good because it is a lie... It is up to man to be deep and true, not good. Indeed, being good is a relative notion. It's only good covering up the bad. [PDS 9]
• There is no culprit. There are only clumsy people. Clumsy in words, clumsy in actions, clumsy in love. [Anonymous]
• When you seek the society of men, remember that your aim is to find that which is beautiful and good in them. Then you will see the good in everything. [MAM 1]

E1.9. To desire

• No one can act according to my desire, everyone acts according to his desire. [PDS 1]
• All psychological problems can be reduced to a single impossible desire : that of being other than what one is. [EHM 1]
• Desiring something else and rejecting what is are one and the same thing, and the root of all suffering. [DEA 1]
• You are not looking for what is, you are looking for what you desire. [Anonymous]
• To find what you want, all you have to do is see what continually comes without you looking for it. This is what you really want. [PDS 4]
• Svâmiji said : "Not without desire but free from desire." [DAF 1]
• When you kill desire, you acquire powers. But unlike the Bhagavad Gîtâ, the Upanisads teach : "When one is free from desires, one finds peace." [RFD 1]
• Svâmiji said : "To be free is to be free from the "I want" and the "I don't want". Here again being free from desire does not mean having no physical sensations. Thus "to be hungry" is a physical sensation, a sensation appeased by the absorption of food. Desire, mental activity, intervenes when one prefers this or that particular food." [RFD 2]
• All desire is infinite. It is normal to dream of always having more, but the outside world is a limited world. How can a limited world fulfill, satisfy an unlimited desire ? [CSO 1]
• To free oneself from desire, it must be satisfied while knowing that no desire can be satisfied. [PDS 4]
• The question arises : "Why are you not satisfied?" For what ? Because a desire can never be satisfied. For what ? Because the desire belongs to you while its satisfaction depends on the outside. But the outside is not you. Let your desire appear as a need. The desire then will disappear immediately. [PSP1]
• (The desire) Instead of trying to suppress it or to bully it, Swâmi Prajnânpad advised to experience it consciously while remaining attentive to the result obtained (with a size restriction, that of not harming others). Until, from disappointments to complete or partial successes, it can fade by itself and fall like a ripe fruit. [DSD 9]

E1.10. To act

• Thoroughness in the preparation, concentration in the execution, freedom in the face of the result, such can be stated the secret of the action. [DSD 10]
• Venkateshvar wrote : "The effect of action is to reduce separation, that is the distance which separates the subject from the object he desires." [RFD 6]
• There are two types of actor in words : the one who speaks to speak and the one who speaks to give. The first affirms his opinions, the second overflows with compassion. [Anonymous]
• Those who are established in certainty no longer need to convince others at all costs of the correctness of their convictions. [DSA 17]
• Svâmiji said : "He who feels hurt cannot help being aggressive. The victim reacts like an assassin. So the victim and the assassin are two opposite sides, two aspects of the same experience." [RFD 1]
• You complain : "He insulted me". The other simply said a few words. But I felt insulted. I felt hurt. This action, this effect, the anger, or any other emotion, where does it occur ? It was he who spoke. This is where the words were spoken. But the reaction took place here. How ? The words were spoken there, and the reaction took place here ?... How absurd ! Isn't it comical ? If the reaction is here, the cause must also be here. Every emotional reaction has its root in me and it is I who am responsible for all these emotional reactions, and not the outside. [PSP1]
• Svâmiji said : "No one acts for the sake of evil, but everyone acts for the sake of good as he understands it." [DSA 15]
• Right action comes from a silent mental. Activity comes from a restless mental. [Anonymous]
• Svâmiji said : "No one can do anything for anyone. You are the creator of your own world. Only you can do anything for yourself." [RFD 3]
• Be free from emotion, then act. You will get the result and not a result. Knowledge must come intellectually, pass through the feelings and from there manifest in action. [PDS 5]
• It is no longer you who act, but the divine energy which acts through you. [DSA 10]
• No one, saint or sage, has ever acted for himself alone. Everything the sage does for another, he does for himself. But instead of his "self" being limited to his small person, he has become vast like the whole of humanity. Nothing and no one is foreign to him. [DSA 17]

E1.11. To live in society

• The other is other. If I want to continue to live in society, I have to adapt to what the other is, to what he expects of me. Adapting does not mean being passive, but changing what can be changed, taking into account the situation and the conditions of the moment. Effective action implies knowledge and information. [RFD 1]
• What makes a good manager is his ability to take advantage of the best of each employee. Like a sage, he knows how to appreciate the bright side of everyone without ever condemning the dark side. [Anonymous]
• How should a child be trained ? Svâmiji said : "be strong but not harsh, firm but not severe." [DSA 19]
• Gurdjieff said : "On the outside play your part. On the inside never identify yourself with anyone." [BTC 1]
• Svâmiji said : "Inwardly, be actively passive", i.e. watchful passivity, "and outwardly, be passively active" i.e. be active not from your egocentric demands and your desire to succeed at all costs but from a state that in a completely different language would be called "submission to the divine will". [DSA 17]
• Deliberate neutrality does not mean indifference but discernment. [Anonymous]
• Svâmiji said : "All the social rules to which you conform are valid when you act in society. But for yourself ? They have no value. So everything that happens in you is neutral. It is neither a sin, nor a virtue. Generally speaking you can see that morality is immoral. Only the truth is moral." [RFD 2]
• Svâmiji said : "The animal is subject to nature. Man fights against nature. The wise man achieves unity with nature by accompanying it in its movement." [RFD 1]

E1.12. To give

• Before giving, check if the other is in a position to receive. It is the ability to receive that justifies giving. If you try to give anyway, you devalue what you give. [PDS 1]
• To give yourself you have to own yourself, otherwise who gives what ? [DSA 23]
• Love is like water poured into a glass. If you feel like you are filling up then you are receiving love, you are loved. If you feel like you are emptying yourself then you are losing something, you are suffering, and you can only give your suffering. If you feel like you are filling up to the point of overflowing then you are giving love, you really love. [Anonymous]
• The true gift is an overflow. You are so fulfilled by your inner plenitude that it only overflows. [Anonymous]
• Svâmiji said : "Giving is possible only when, in the mind of the one who gives, there remains no feeling "that he gives" " [RFD 5]

E1.13. To help others

• Advice should not be wasted on people whose need has not arisen. You must first make sure that the other is ready to receive and follow the advice. The teacher must wait until the question is asked, that is, until a doubt has arisen in the student's mind. Doubt, doubt, doubt must appear first. This is the criterion of the need for assistance. [PDS 4]
• Either learn carefully what you don't know, or teach clearly what you know. [Anonymous]
• You cannot lead anyone beyond the point you have reached yourself. [MRD 1]
• Experience is a lantern that illuminates only the wearer [Céline]. To transmit it, you will have to carry the other to the altitude from where he will see clearly himself. [Anonymous]

E1.14. To die

• Death is an aspect of life, and we modern Westerners have forgotten that. We contrast death and life instead of contrasting death and birth, and remembering that life is the ceaseless play of death and birth. [DSA 10]
• By changing, one thing does not become something else. The first ceases to exist and the second springs into existence. [SNR 1]
• ...So it is with the human brain. Some neurons die and are replaced by other neurons. No transformation. No rebirth. Simply dead of a cell which gives way to another cell ready to live. [Anonymous]
• No one is born, no one dies. There is birth and death, and no one to take part in this phenomenon. [PDS 4]
• This world is not our home. We are a passing traveler... We entered this world empty-handed and alone, and we will leave it empty-handed and alone. [GKG 1]
• When life is lived fully, moment by moment, as a series of unique experiences, then death will be lived in joy as a new experience to be lived. [Anonymous]

E1.15. Sources relating to life laws

[ARI 1] Association pour le Rayonnement Culturel Indien, Citation de Mata Amritanandamayi, La Lettre N°3 de l'ARCI, 2ème trimestre 1987
[BTC 1] Bouchet Christian, Gurdjieff - qui suis-je, Pardès 2001
[CSA 1] Comte-Sponville André, De l'autre côté du désespoir - Introduction à la pensée de Svâmi Prajnânpad, Accarias-L'Originel 1997
[CSO 1] Cambessédès Olivier, Le quotidien avec un maître Svami Prajnanpad, Accarias L'Originel 1995
[DAF 1] Desjardins Arnaud et Farcet Gilles, Confidences impersonnelles, Critérion 1991
[DAF 2] Desjardins Arnaud et Farcet Gilles, Regards sages sur un monde fou, La Table Ronde 1997
[DAL 3] Desjardins Arnaud et Loiseleur-Desjardins Véronique, La voie et ses pièges, La Table Ronde 1992
[DAL 4] Desjardins Arnaud et Loiseleur-Desjardins Véronique, L'ami spirituel, La Table Ronde 1996
[DEA 1] Delaye Alain, Sagesses concordantes - Quatre maîtres pour notre temps : Etty Hillesum, Vilama Thakar, Svâmi Prajnânpad, Krishnamurti, Volume I, Accarias-L'Originel 2003, 2011
[DSA 7] Desjardins Arnaud, A la recherche du Soi 1 - Adhyatma yoga, La Table Ronde 1977
[DSA 8] Desjardins Arnaud, A la recherche du Soi 2 - Le vedanta et l'inconscient, La Table Ronde 1978
[DSA 9] Desjardins Arnaud, A la recherche du Soi 3 - Au-delà du moi, La Table Ronde 1979
[DSA 10] Desjardins Arnaud, A la recherche du Soi 4 - Tu es cela, La Table Ronde 1980
[DSA 15] Desjardins Arnaud, La voie du coeur, La Table Ronde 1987
[DSA 17] Desjardins Arnaud, Zen et Vedanta - Commentaire du Sin sin ming, La Table Ronde 1995
[DSA 19] Desjardins Arnaud, Retour à l'essentiel, La Table Ronde 2002
[DSA 21] Desjardins Arnaud, Bienvenue sur la voie, La Table Ronde 2005
[DSA 23] Desjardins Arnaud, Lettres à une jeune disciple, La Table Ronde 2006
[DSD 1] Desjardins Denise, De naissance en naissance, La Table Ronde 1977
[DSD 3] Desjardins Denise, Mère sainte et courtisane, La Table Ronde 1983
[DSD 7] Desjardins Denise, La route et le chemin - Carnet de voyage et d'ascèse, La Table Ronde 1995
[DSD 9] Desjardins Denise, Conteurs, Saints et Sages - Des Pères du désert à Swâmi Prajnânpad, La Table Ronde 1998
[DSD 10] Desjardins Denise, Petit traité de l'action, La Table Ronde 1999
[EHM 1] Edelmann Eric, Humbert Olivier et Dr Massin Christophe, Swâmi Prajnânpad et les lyings, La Table Ronde 2000
[FTG 1] Farcet Gilles, Arnaud Desjardins ou l'aventure de la sagesse, La Table Ronde 1987
[FTG 3] Farcet Gilles, La transmission selon Arnaud Desjardins, Le Relié 2009
[GKG 1] Guéshé Kelsang Gyatso, Vivre une vie pleine de sens - Mourir dans la joie, Tharpa France 2017
[GKG 2] Guéshé Kelsang Gyatso, Transformez votre vie. Un voyage plein de félicité, Tharpa France 2009
[LRF 1] Leboyer Frédérick, Portrait d'un homme remarquable - Svami Prajnanpad, Critérion 1991
[LRV 1] Loiseleur-Desjardins Véronique, Anthologie de la non dualité, La Table Ronde 1981
[MAM 1] Mâ Ananda Moyî, L'enseignement de Mâ Ananda Moyî, traduit par Josette Herbert, Albin Michel 1974
[MRD 1] Marol et Roumanoff Daniel, Sois sage, La Table Ronde 1994
[NIL 1] Nduwumwami Louis, Krishnamurti et l'éducation, Du Rocher 1991
[OPD 1] Ouspensky Petr Demianovitch, L'homme et son évolution possible, Denoël 1961 puis Accarias L'Originel 1999
[OPD 2] Ouspensky Petr Demianovitch, Fragments d'un enseignement inconnu, Stock 1974
[PDS 1] Prajnanpad Svami, L'art de voir, Lettres à ses disciples - Tome 1, Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 1988
[PDS 2] Prajnanpad Svami, Les yeux ouverts, Lettres à ses disciples - Tome 2, Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 1989
[PDS 3] Prajnanpad Svami, La vérité du bonheur, Lettres à ses disciples - Tome 3, Traduction de Colette et Daniel Roumanoff, Accarias L'Originel 1990
[PDS 4] Prajnanpad Svami, A B C d'une sagesse, Paroles choisies par Daniel Roumanoff, La Table Ronde 1998 puis Albin Michel 2009
[PDS 5] Prajnanpad Svami, L'éternel présent - Questions et réponses - Entretiens avec Pierre Wack, Traduction de Daniel Roumanoff, Accarias-L'Originel 2002
[PDS 6] Prajnanpad Svami, Les formules de Swâmi Prajnânpad commentées par Arnaud Desjardins, Formules et commentaires rassemblés par Véronique Desjardins, La Table Ronde 2003
[PDS 7] Prajnanpad Svami, Le but de la vie - Un été plein de sagesse, Entretiens avec Roland de QuatreBarbes été 1966, traduits par Daniel Roumanoff, Accarias-L'Originel 2005
[PDS 8] Prajnanpad Svami, Svâmi Prajnânpad pris au mot - Les Aphorismes, Recueillis et traduits par Frédérick Leboyer, Accarias-L'Originel 2006
[PDS 9] Prajnanpad Svami, Ceci Ici A présent - Seule et unique réalité, Entretiens avec Frédérick Leboyer (première série, janvier et février 1963), Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 2006
[PDS 10] Prajnanpad Svami, La connaissance de soi - Citations commentées des Upanishad et histoires (tome 1), Mises en forme par Daniel Roumanoff, Accarias-L'Originel 2008
[PSP 1] Prakash Sumangal et Prajnanpad Svami, L'expérience de l'unité, Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 1986 puis 2013
[RFD 1] Roumanoff Daniel, Svâmi Prajnânpad - Tome 1 Un maître contemporain - Manque et plénitude, La Table Ronde 1989, puis regroupé avec le Tome 3 chez Albin Michel 2009 sous le titre "Tome 1 Les lois de la vie"
[RFD 2] Roumanoff Daniel, Svâmi Prajnânpad - Tome 2 Le quotidien illuminé, La Table Ronde 1990, puis Albin Michel 2009
[RFD 3] Roumanoff Daniel, Svâmi Prajnânpad - Tome 3 Une synthèse Orient Occident, La Table Ronde 1991, puis regroupé avec le Tome 1 chez Albin Michel 2009 sous le titre "Tome 1 Les lois de la vie"
[RFD 4] Roumanoff Daniel, Candide au pays des Gourous - Journal d'un explorateur de l'Inde spirituelle, Dervy 1990
[RFD 5] Roumanoff Daniel, Svâmi Prajnânpad - Biographie, La Table Ronde 1993
[RFD 6] Roumanoff Daniel, Psychanalyse et sagesse orientale - Une lecture indienne de l'inconscient, Accarias L'Originel 1996
[SNR 1] Srinivasan Ramanuja, Entretiens avec Svami Prajnanpad, Traduction de Colette Roumanoff, Accarias-L'Originel 1984

E2. Hypnosis, between science and mystery

This chapter explores the different facets of hypnosis, including its side effects and potential dangers, the world of show hypnosis, self-hypnosis techniques, as well as the legal and ethical aspects that govern its use.

1. Definition
2. Side effects
3. Dangers
4. Show hypnosis
5. Self-hypnosis
6. Legal framework
7. Ethics of hypnosis
8. Sources

E2.1. Definition :

Hypnosis is an ancient technique dating back more than 6000 years in the Orient and to the end of the 18th century for modern hypnosis. It produces a modified state of consciousness located between wakefulness and sleep.
More precisely, it allows to induce by speech a particular state of consciousness characterized by indifference to the outside and a greatly increased capacity to receive suggestions (in particular the voice of the hypnotist) [ANM][INS][ MAB].
At the psychological level, hypnosis induces a state of deep relaxation based on freely given suggestion [AFI].
At the neurological level, hypnosis involves a change in brain activity, including a decrease in activity in regions associated with processing sensory information and an increase in activity in regions associated with attention and suggestion [MAB].
Hypnosis is used in different medical sectors [MIN] :
- anesthesia (hypnosedation), to reduce the stress of the operation, or even allow certain operations without resorting to general anesthesia, which is replaced by a sedative medication and quality local anesthesia ;
- pain management (hypnoanalgesia), particularly in obstetrics to reduce labor pain ;
- psychotherapeutics (hypnotherapy), to help people achieve a state of deep relaxation allowing them to work on their problems (fear, stress, blockage, etc.) without causing unwanted side effects.

E2.2. Side effects :

Side effects of hypnosis are as follows :
- Temporary and mild effects : headaches, fears, sadness, disorientation, etc. [CFH1][MAB]
- Rare but serious effects : hallucinations, altered memories, personality change, depression, suicidal impulses, etc. [CFH1]
These side effects are not always the consequence of hypnosis as such. They may arise due to the pre-existing vulnerability of the subject, the practitioner's inexperience in dealing with psychotherapeutic problems, the use of inappropriate suggestions, the inability to erase non-therapeutic suggestions or to fully redirect the patient through adequate debriefing [CFH1].
These reactions occur more often in certain contexts such as show hypnosis, or when the training and experience of the practitioner are insufficient [CFH1].

E2.3. Dangers :

The dangers of hypnosis are as follows :
- Incompetent or clumsy hypnotist : he can in particular plunge a person back into a past trauma without knowing how to manage the situation [ATK].
- Absence of prior diagnosis : a practitioner who does not know how to use the hypnosis tool without prior clinical, psychological or somatic knowledge, will not be able to distinguish between the psychological expression of a serious pathology and a disorder that may be sensitive to a hypnotic approach. Thus, anxiety can be a sign of a pulmonary embolism, a myocardial infarction and many other severe disorders. It is therefore appropriate for the practitioner who is going to use hypnosis to be able to have explored all the possible causes of the disorder, or failing that, to have verified with the patient's treating physician that the pathology has been explored and diagnosed or that the psychosomatic origin has been demonstrated [CFH1].
- Non-compliance with medical contraindications : hypnosis should not be practiced on people with heart disease, epilepsy or serious psychopathology (delusions, psychosis, paranoia, etc.) [CFH1][MAB].
- False memories : the unconscious can produce coherent but false responses, often in an attempt to relieve suffering. Hypnosis accentuates this phenomenon [CFH3][BEN]. Any practitioner must refuse any patient request aimed at rediscovering forgotten memories [CFH3] or verifying the reality of a memory (for example, women who believe they were abused as children) [BEN].
- Poor management of emotional reactions after hypnosis, which can lead to persistent discomfort [CFH1][UNI][ATK].

E2.4. Show hypnosis :

Show (or street or fair) hypnosis is a hypnosis technique close to therapeutic hypnosis, practiced for commercial or occult purposes which has nothing to do with the patient's interest [ATK].
Unlike therapeutic hypnosis, the show hypnotist does not establish rapport with the subject, adopt an authoritative and directive approach, do not debrief individually and do not interrupt the hypnotic trance if necessary [CFH2].
The individual on stage volunteered to play the game and showed particular skills in the trance state during the pre-test carried out by the hypnotist. Added to this is the group effect which reduces the unconscious resistance of the individual [UNI]. The show then consists of attracting the audience by producing spectacular reactions (for example, seeing a subject think he is a chicken on a wall) [GRO].
Many people hypnotized on stage say that, although they are aware of being ridiculed, they paid to go on stage, people watch them and they have an astonishing experience [SAR].
Show hypnosis presents dangers that therapeutic hypnosis does not have: dangers in particular for people with with heart disease, epilepsy, serious pathology or psychologically fragile [CFH1][MAB]. Added to this is the non-management of possible emotional reactions upon exiting hypnosis [CFH1][UNI][ATK].

E2.5. Self-hypnosis :

Self-hypnosis is hypnosis practiced alone, without the help of a practitioner. Like meditation, self-hypnosis is a physical and mental relaxation technique. But unlike meditation :
- The purpose is therapeutic (resolution of a problem) and not spiritual (search for inner peace).
- Relaxation involves an active suggestion or visualization (and not a simple caring attention to the experience of the moment) aimed at achieving a specific objective, such as stress management or improving self-confidence.
- Awareness of the external world disappears in favor of an internal look, while in meditation consciousness is both internal (thoughts, emotions, sensations) and external (perceptions of the environment). The person being hypnotized feels like they are dissociated, with one part of them observing what the other part of themselves is doing, while the meditator is aware of everything that is happening in and around them [PIC].

E2.6. Legal framework :

In France, there is no legal framework to regulate the practice of hypnosis. There is only teaching of hypnosis at the university, associative and private level, as well as various ethical codes of hypnosis.
Two types of hypnosis practices can be distinguished [SEN] :
- Therapeutic hypnosis is practiced by health professionals in the medical field (doctors, psychiatrists, psychotherapists and clinical psychologists) and paramedical field (dentists, midwives, nurses, physiotherapists, occupational therapists and psychomotor therapists).
- Hypnosis known as "better being" is practiced by other professionals under various names : hypnotherapist, hypnopractitioner, hypnologist, hypnosis psychopractitioner, brief therapy practitioner, etc. They must not use certain reserved words such as : "psychotherapist", "patient", "consultation", "diagnosis", "prescription", under penalty of "illegal practice of medicine". We therefore do not speak of "patient" but of "client".
In France the exercise of therapeutic hypnosis in a context other than medical is similar to the illegal exercise of medicine (No. 09-81.778 of the Criminal Chamber of March 9, 2010, and article L.4161-1 of the public health code) [SEN][CFH4].

E2.7. Ethics of hypnosis :

The Confederation Francophone Hypnosis and Brief Therapies (CFHTB) published in 2003 an ethical code of hypnosis based on medical ethics, the principles of which are as follows [CFH4] :
    1. The best interests and well-being of the patient are the highest priority.
    2. Hypnosis is considered a complement to other forms of clinical or supportive scientific practices.
    3. The hypno-practitioner will limit his scientific or supporting clinical use of hypnosis to the areas of competence recognized by the regulations of his profession or the uses relating to it.
    4. The hypno-practitioner undertakes not to use hypnosis or brief therapy as a form of distraction or spectacle.
    5. In all cases, the transition to the practice of hypnosis will remain conditional on obtaining a complete qualification in the professional field considered.
    6. The communication of information relating to hypnosis to the various media is accepted to the extent that it is based on precise scientific knowledge.

E2.8. Sources :

[AFI] AFIS, L'hypnose : charlatanisme ou avancée médicale ?.
[ANM] Académie nationale de médecine, Thérapies complémentaires - acupuncture, hypnose, ostéopathie, tai-chi - leur place parmi les ressources de soins, rapport de la séance du 5 mars 2013.
[ATK] Jean-Marc Atkins, Quels sont les dangers de l'hypnose (ericksonienne) ?
[BEN] Jean-Marc Benhaiem, L'hypnose ne permet pas de retrouver la mémoire de faits réels..., Huffpost
[CFH1] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Risques et dangers de l'hypnose
[CFH2] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Risques et dangers de l'hypnose : hypnose de spectacle
[CFH3] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Risques et dangers de l'hypnose : les faux-souvenirs
[CFH4] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Livre blanc de l'hypnose clinique et thérapeutique
[FTB] I2FTB, Quel cadre légal quand on fait de l'hypnose ou PNL ?
[GRO] Laurent Gross, EMDR, Hypnose ericksonienne, médicale et thérapeutique à Paris
[IFH] IFH, Institut Français d'Hypnose, Lexique en hypnose thérapeutique
[INS] Inserm, Evaluation de l'efficacité de la pratique de l'hypnose - 2015
[MAB] Emmanuel Mabin, e-academy.fr, Mieux comprendre l'hypnose
[MIN] Ministère de la Santé et de la Prévention
[PIC] Caroline Pico, Similitudes et différences entre hypnose et méditation
[SAR] Corinne Sarazin, Les dangers de l'hypnose eriksonienne ou autre
[SEN] Sénat, Réponse du Ministère des solidarités et de la santé publiée le 14/02/2019
[UNI] Unitheque, Quels sont les métiers de l'hypnose ?

E3. Smells and flavors

Smell and taste are the two senses that aroused the least interest from scientific researchers until the 1960s.
Today, we know that the sensory perception of smells and flavors is a subtle mix between universal principles, personal perception and culture.

1. Smells
2. Flavors

E3.1. Smells

Smells are molecules detected chemically by olfactory receptors located in the nasal cavity.
They can take two distinct routes : a direct route, called orthonasal, located in the nose (concept of "smell") or an indirect route, called retro-nasal, located in the back of the throat (concept of "aroma" released by food in the mouth).
There is to date no universal consensus on the categorization of smells. Only perfumery and oenology have produced specific classifications.
The table below allows you to simply categorize smells according to their effects (unpleasant/pleasant) and their origins (mineral, plant, animal, human).

• Unpleasant
  • Industrial chemistry : sulfuric acid, ammonia, rubber, bleach, gasoline, domestic gas, paint, phosphorus, plastic, sulfur, varnish...
  • Animal and human waste : urine, droppings, manure, fart, perspiration
  • Plant and animal decomposition : fermentation, rot, carrion
  • Stinky plant : spotted arum, foul goosefoot, ginkgo biloba female, common serpentgrass...
  • Exterior : cigarette, smoke, exhaust gases, ozone (electrification), urban pollution , pigsty, tobacco
  • Home : wastewater, sewage, septic tank, humidity, animal litter, mold, trash
  • Cooking : garlic, frying, onion, tripe, vinegar
• Mineral
  • Soil : chalk, tar, earth
  • Exterior : swimming pool chlorine, geosmin (smell of freshly plowed or wet earth), marine iodine
• Plant
  • Wood : bark, leaf, resin
  • Grass : hay, freshly cut grass, humus, straw
  • Plant without flowers : mushroom, fern, moss, truffle
  • Flower : jasmine, lavender, orange, rose, lime, verbena, violet...
  • Fruit : almond, coffee, lemon, strawberry, raspberry, hazelnut, peach, pear...
• Animal
  • Body : leather, musk
  • Production : beeswax, milk, honey, egg
• Human
  • Body : skin
  • Industrial chemistry : perfume, soap, shampoo...
  • Home : candle, air freshener, laundry detergent...
  • Cooking : alcohol, herbs, caramel, spices, cheese, cake, oil, hot bread, freshly popped popcorn, fish, wine...

Sources :

Claude Boisson, "La dénomination des odeurs : variations et régularités linguistiques", Intellectica, 1997/1, 24, pp. 29-49.
Sophie David, Danièle Dubois, Catherine Rouby, Benoist Schaal, "L'expression des odeurs en français : analyse lexicale et représentation cognitive", Intellectica, 1997/1, 24, pp. 51-83.
Dico du Vin, Odeurs du vin, nouvelle classification, Dico-du-Vin 2023.
Danièle Dubois, "Des catégories d'odorants à la sémantique des odeurs", Terrain, 47 | 2006, 89-106.
Camille Gaubert, 03.05.2022, "Notre perception des odeurs n'est que très peu liée à notre culture", Cerveau et Psy.
André Holley, "Le physiologiste et la catégorisation des odeurs", Intellectica, 1997/1, 24, pp. 21-27.
L'Atelier du Vin, Guide des arômes du vin et de leur perception en oenologie.
Hervé-Pierre Lambert, "L'imaginaire, les neurosciences et l'olfactif : confirmations et extrapolations", IRIS, 33 | 2012, 37-51.
C. Sulmont-Rossé, I. Urdapilleta, "De la mise en mots des odeurs", chapitre 28 (pp. 373-382) du livre : Odorat et Goût : de la neurobiologie des sens chimiques aux applications agronomiques, industrielles et médicales, Edition QUAE.
Lucía Poyo Vallina, 24 nov. 2022, "Les 10 principales odeurs perçues par l'odorat humain", Divain, .
Wikipedia, Rétro-olfaction.

E3.2. Flavors

Flavors are molecules detected chemically by taste receptors located on the taste buds of the tongue.
Other sensations in the mouth, also called "flavors" in the broad sense, do not involve the taste buds and are sensory (olfactory, auditory, visual) and somesthetic (thermal, tactile, proprioceptive (position and movement) and nociceptive (pain)).
The table below describes the basic flavors, "flavors" being taken in the broad sense. They can then combine with each other to form more elaborate taste sensations.

• Taste level : Flavors detected by the taste buds of the tongue :
  • sweet or sweet (examples : sucrose, sugar)
  • sour (examples : citric acid, lemon juice)
  • salty (examples : sodium chloride, table salt)
  • bitter (examples : broccoli, caffeine, quinine present in particular in tonic-type drinks)
  • tasty or delicious or "umami" in Japanese (monosodium glutamate (MSG) which is the dominant flavor of breast milk and also a food additive (code E621) present in particular in some yeasts, soybeans and Asian broths)
• Olfactory level : "Flavors" detected retro-nasally in the form of aromas released by foods in the mouth.
• Auditory level : "Flavors" detected by hearing :
  • crispy, crunchy, brittle (examples : biscuit, chips)
• Visual level : "Flavors" detected by sight :
  • appetizing (examples : food on the plate, wine in the glass)
• Somesthetic level : "Flavors" detected by the trigeminal nerve of the face that innervates the mucous membranes of the mouth, nose and eyes :
  • spicy (examples : ginger, mustard, chilli, pepper) detected at the nociceptive level
  • sparkling (example : carbon dioxide present in "soda" type drinks) detected at the tactile level
  • fresh, cold (example : fresh mint) detected at the thermal level
  • lukewarm, warm (example : soup) detected at the thermal level
  • iced, hot detected at the nociceptive level
  • astringent (examples : lingonberry, banana or persimmon too green, fresh walnut, tannin, tea) detected at the tactile level by the tightening of taste buds
  • texture of rough, grainy, fibrous, pasty, viscous, smooth, juicy... type detected at the tactile level by the surface of the oral tissues
• Somesthetic level : "Flavors" detected by the trigeminal nerve of the face that innervates the joints, ligaments, tendons and muscles of the lower jaw :
  • texture of soft, hard, elastic, brittle... type detected at the proprioceptive level during masticatory movements
• Somesthetic level : "Flavors" detected by the trigeminal nerve of the face that innervates the tendons and muscles of the tongue :
  • shape of cube, sphere, edge... type detected at the proprioceptive and tactile level during lingual movements
• Other "flavors" whose origin is not clearly identified to date :
  • bland or tasteless (example : pure water)
  • metallic (examples : iron, zinc)
  • fatty or oily or "oleogustus" (example : cooking oil)
  • starchy or alcaline (starch present in pasta and other starchy foods)
  • calcium
  • licorice

Sources :

Le Thi Maï Allafort, Connaissez-vous les mots du goût ? Lorsque les textures font le plaisir !, Marie Claire.
Christine Belloir, Récepteurs gustatifs humains : étude des relations structure-fonction, Thèse 2019, Université de Bourgogne.
Diane Boivineau, Evaluation gnoso-praxique linguale des enfants avec trouble structurel du langage oral, Mémoire 2013/2014, Université Paris VI.
Loïc Briand, "La chimie du goût", CultureSciences-Chimie.
Juliette Defossez, Vers un langage du goût : approche expérimentale d'une communication multimodale à destination des mangeurs, Thèse 2014, Université de Bourgogne.
Audrey Dufour, 24/01/2017, "Comment reconnaît-on les saveurs ?", La Croix.
Goûts et Papilles, C'est quoi le goût ? Odeur, saveur, flaveur....
FasterCapital, Au-delà du goût : comment la texture influence notre perception des aliments.
Claire Gresser, Contribution à l'étude de la composante trigéminale dans la posture cervico-faciale, Thèse 2005, Université de Lorraine.
Tanya Lewis, 5 octobre 2021, "Ce que les piments peuvent nous apprendre sur la douleur", Pour la Science.
Christophe Otte, Olivier Otte, Régulation des dysfonctions maxillo-faciales de l'enfant, Clinique OPS.
Dale Purves, George J. Augustine, David Fitzpatrick, Lawrence C. Katz, Anthony-Samuel LaMantia, James O. McNamara, Neurosciences - Les sens chimiques, DeBoeck
Rapport du groupe PNNS - Qualité gustative des aliments et environnement des repas : restauration scolaire, hospitalière et aide alimentaire, décembre 2010.
Si on me coupait la langue, pourrais-je toujours savourer mes repas ?, La sensation trigéminale.
Wikipedia, Goût.
Wikipedia, Thermorécepteur.

F. Society

F1. Planned obsolescence and consumer products

Current or durable consumer products offered on the markets do not always have the expected quality. The main causes are the following :

1. "Construction" defect of the product
2. Non-optimal user manual
3. Non-optimal consumer service
4. Premature and planned obsolescence of the product
5. Sources

F1.1. "Construction" defect of the product

Three types of fault exist :

• Design defect : the defect is often irremediable.
• Correct but flanged design : the consumer is not clearly informed.
  Example 1 : many oil-filled electric radiators on casters have a reduced weight reducing their heat accumulation power and consequently their action range.
  Example 2 : a large number of motion detectors with PIR (Passive InfraRed) technology operate chaotically outside the robustness limits of the electronic card or the operating ranges of the detection algorithm, particularly when they are placed outdoors in the presence wind, rain or humidity.
• Produce defect : the test campaigns before leaving the factory are not always sufficient and a large number of products on the market are defective on their first use.

In France nearly 10 % of electronic devices purchased on the Internet are returned due to non-compliance.
For domestic electrical devices, the faulty component is often the electronic block of the device (examples : freezer, steam iron, thermal resistance of towel dryers, lighting of bathroom cabinets with touch control, outdoor solar light garland, DVD player).

F1.2. Non-optimal user manual

The product user manuel is sometimes succinct, poorly structured, roughly translated into French or written only in English, which does not allow consumers to use the product easily and appropriately.

F1.3. Non-optimal consumer service

Access to consumer service is not always easy (examples : unclear access methods, premium rate telephone number, unspecified waiting time).
Furthermore, the processing of requests and complaints is sometimes disconcerting or even flawed, with some operators not always having sufficient training in the products and services in the catalog, in internal procedures and in IT tools.

F1.4. Premature and planned obsolescence of the product

Planned obsolescence is a market practice justified by manufacturers for economic (see Consumer society), technical and risk prevention reasons. The consumer suffers the consequences : he is frustrated when he notices that the effective lifespan of his product does not correspond to the lifespan he expects.
But the causes of obsolescence are not only linked to the producer. They may occur during sale, distribution or consumption. This is why we speak more widely of premature obsolescence.
Different types of premature obsolescence can shorten the life of consumer products [CLI][HIP] :

• Product of flanged design (see paragraph no. 1 above) whose use precautions or use limits are not clearly displayed.
• Product whose functioning is degraded after a certain use period (example : women's tights which generally do not last more than six uses, whereas historically nylon stockings were extremely robust and resistant) ;
• Product whose operation is blocked after a certain use period (example : some printers equipped with a smart chip, forcing the ink cartridges to be replaced before they are empty) ;
• Product of which one of the hardware components is weakened from the design stage (examples : computer monitor, battery of digital landline telephones when permanently charged) ;
• Product whose defective parts are almost inaccessible (examples : bearings of front-loading washing machines, electric car batteries) or cannot be removed (example : some smartphones and laptops whose battery or screen is fixed with industrial glue or screws not standard) ;
• Product whose spare parts or accessories are non-existent in the manufacturers' catalog (example : LED and transformer integrated in the luminaires) or taken out of the catalog (example : old coffee maker bowl) or incompatible with the product (examples : new battery, new consumable) ;
• Product whose maintenance or repair is expensive compared to the residual value of the product or the purchase price of a new product (economic obsolescence) ;
  
• Product whose software support is discontinued and does not allow updating or downloading applications (software obsolescence) ;
• Operational product but become outdated in the eyes of consumers (cultural or aesthetic or psychological obsolescence).

France is the first country in the world to have criminalized planned obsolescence through article L. 441-2 of the Consumer Code dated March 14, 2016.
Law n° 2021-1485 of November 15, 2021 relating to the reduction of the digital environmental footprint in France (REEN law) then modified this article by redefining the offense as follows : "The practice of planned obsolescence is prohibited which is defined by the use of techniques, including software, by which the person responsible for placing a product on the market aims to deliberately reduce its lifespan".
Warning : there may be "obsolescence" without it being planned. It is up to the consumer to provide proof of the voluntary intention of the manufacturer to reduce the life of the product : difficult or even impossible task.

One of the solutions aimed at combating planned obsolescence is the services rental. Instead of owning a good, we would pay for the service rendered. Companies would then benefit from manufacturing durable and easily repairable goods (example : Xerox in the professional photocopier market) [WIK].


F1.5. Sources relating to planned obsolescence :

[HIP] HIPPOCAMPE, Usages numériques et terminaux.
[CLI] LE CLIMATOSCOPE, L'obsolescence prématurée de nos produits de consommation : un débat à remodeler.
[WIK] WIKIPEDIA, Obsolescence programmée.

F2. Consumer society

The consumer society is a type of society within which consumers are encouraged to consume goods and services on a regular and abundant basis [JDN].

1. Introduction
2. Results
3. Conclusions
4. Sources

F2.1. Introduction :

The consumer society appeared in Western countries from the second half of the 20th century, at the same time as some trends such as the women emancipation, industrial and technological innovation, globalization of trade.
The economy will then rely on the production capacities of companies as well as on the consumption capacities of citizens. It will increase the living standard of a large number of citizens in terms of comfort and material well-being, by increasing access to goods and services in volume and diversity.
But gradually a new paradigm is emerging : "consume more, produce more, earn more". Producers and consumers then mechanically become hyper-producers and hyper-consumers. The first ones offer an abundant supply based on products with a limited lifespan (Premature obsolescence). The seconds have demands that go well beyond their primary needs.

F2.2. Results :

This situation, where producers and consumers are closely linked around the industry of "desire", has resulted in the following consequences on the individual and their environment :

1. On an information level, the media (press, edition, poster, radio, television, cinema, Internet network, telecommunications) broadcast to the consumer (reader, listener, spectator, Internet user) a mass of more or less accurate information, amplified by social networks and content sharing platforms.
Broadcast can take different forms :

• Overload information : massive dissemination of disparate information which imposes itself as a deafening source of noise.
• Obfuscation (or jamming) : massive dissemination of false, imprecise or flattering information, in order to drown relevant, embarrassing or confidential information in a large volumevolume of data. Examples : creating a diversion with minor events to pass unnoticed information that is embarrassing to a government ; introducing flattering information into forums to correct a bad reputation [TOU].
• Disinformation : dissemination of false or biased information (quote truncated or taken out of context, fake news, propaganda ("intox"), hoax, rumor, buzz, etc.).
• Misinformation : involuntary or accidental dissemination of false information.
• Harmful information : dissemination of exact information for harmful purposes (disclosure of secrets, publication of confidential data, defamation, etc.).
• Non-information : concealment of important information, which may be total (concealment subject to censorship) or almost total (dissemination of vague or incomplete information in such a way that it cannot be said that it is completely concealed).
• Scoop : dissemination of sensational and immediate information showing current events from the focused and biased angle of sensationalism.
• Spam : dissemination of unwanted information for commercial, advertising or malicious (fraud, malware) purposes.

2. On an audiovisual communication level, the media, whose concern is to preserve a market more than to ensure the civic education of the masses, become a source of sensory pollution and overstimulation of the senses to the detriment of useful information [BEN]. See Media violence.

3. On an ecological level, overconsumption encourages waste and the production of waste which pollutes, even if progress is made to recycle it as cleanly as possible.

4. On a nutritional level, overconsumption promotes the appearance of pathologies such as diabetes and obesity.

5. On a professional level, the perpetual creation of new needs can lead to over-indebtedness, overwork or insecurity.

6. On a psychological level, the search for "always more" can lead to continual frustration which generates discomfort, depressive and even aggressive behavior.

7. On a social level, the human being has also become a "product" who must "know how to sell himself", who must enter into "competition", "at war" with everyone and others.

8. On a moral level, consumer objects become ends in themselves leading to a loss of "true purpose".

9. On the human level, social relations become simple means and are therefore artificial. We must then differentiate ourselves from others, in particular by impressing others with symbols of wealth and power to the detriment of the authenticity and depth of human relationships.

10. On a spiritual level, having replaces being, depth, introspection, reflection on identity based on something other than possessions [GUI].

F2.3. Conclusions :

Today the consumer society, which has become a society of overconsumption, is beginning to move towards a society of deconsumption along four axes : individual, community, systemic and environmental :

1. Individual sufficiency which consists of consuming less and differently, favoring quality rather than quantity.
To be applicable at the level of each consumer, this sobriety must be "happy", that is to say without the idea of restriction or sacrifice. Examples : second-hand purchase, recourse to repair, return to essential needs.
This trend would be driven in France by the elderly (with fewer needs), women (attracted towards ecology) and the most qualified (attracted towards a form of daily asceticism) [GOL][CAS].

2. Collaborative economy based on the sharing or exchange between individuals of goods (car, housing, parking, drill, etc.), services (passenger transport, DIY, etc.) or knowledge (computer courses, communities of learning, etc.), with or without monetary exchange, with or without digital networking platform.
By reducing or even eliminating intermediaries, this economic system allows you to moderate your expenses and save money.

3. Circular economy focused on a sustainable strategy which consists of sharing, reusing, repairing, renovating and recycling products and materials for as long as possible so that they retain their value.
In France, we can cite the following examples :

• National harmonization of the color of waste bins subject to selective sorting, in order to guide and facilitate the sorting process. For household waste : green bin for glass, yellow bin for all packaging, gray or black bin for other waste. In companies, sorting is even more selective : blue bin for paper and cardboard, brown bin for bio-waste, other freely colored bins for company-specific waste.
• End of disposable tableware in catering establishments serving on site more than 20 meals simultaneously. Meals are now served in washable and reusable tableware.
• End of systematic printing of receipts. The customer can always request their ticket if they wish.
• Availability of spare parts by manufacturers for a minimum period after purchase (smartphones, laptop computers, household appliances, motorized gardening and DIY tools, motorized personal transport vehicles, sporting and leisure items).
• Display of a repairability index by sellers of electronic and electrical equipment (smartphones, laptops computers, televisions, porthole washing machines, top washing machines, dishwashers, vacuum cleaners, lawn mowers, high-pressure cleaners).
• Market for packaging-free products, sold in bulk and in reusable or reusable containers.
• Second-hand market (used or reconditioned products) making it possible to avoid using new resources to produce them (platforms Vinted, Le Bon Coin, Ebay, Emmaüs, etc.).
• Rental of individual services. Instead of owning a good, the consumer pays for the service provided. Companies then manufacture durable and easily repairable goods (Xerox on the professional photocopier market, Michelin on the truck tire market, etc.).
• Rental of shared services (laundries, etc.).
• Rental of shared goods (cars (Autolib), bicycles (Vélib), books (libraries), etc.).

4. Waste management which consists of collecting it and then transforming it, prioritizing in order: reuse, recycling, elimination [MTE].

• Reusing waste consists of using it again without any special treatment after control, cleaning or repair (worn clothes, car tires reused to protect the hull of boats or trawlers, etc.). Reuse can be simple reuse (returnable bottles refilled after cleaning, etc.).
• Recycling waste consists of transforming it into raw materials (processing of paper and cardboard to make paper pulp, remelting of broken bottles to make new bottles, composting of bio-waste, etc.) or into energy (production of electricity or heat by incineration of waste, methanization of biowaste, etc.).
• The elimination of "ultimate" waste consists of making it disappear by incineration or storage in a dedicated landfill (refusal of sorting after selective collection treatment by sorting centers, household waste, medical waste, paint cans, rubble, bulky items, end-of-life vehicles, etc.).

In France, in 2018, 66 % of treated waste is recycled, 7 % is incinerated with or without energy recovery and 27 % is landfilled [NOT].

F2.4. Sources :

Sources relating to consumer society :
[ADE1] ADEME, Economie circulaire : notions, 2013.
[ADE2] ADEME, Potentiels d'expansion de la consommation collaborative pour réduire les impacts environnementaux, 2016.
[AGE] Agence Lucie, L'économie circulaire.
[ALT] Altermaker, Economie circulaire : définition et exemple.
[BEN] Abdellatif Bensfia, "François HEINDERYCKX (2003), La malinformation. Plaidoyer pour une refondation de l'information", Communication, Vol. 23/2 | 2005, 259-265..
[CAS] Jean-Laurent Cassely, Les diplômés, bons élèves ou cancres de l'alterconsommation ?, in Constructif, juin 2021 (N°59).
[CHI] Chilowé, Comment vivre la sobriété heureuse au quotidien ?.
[DES] Cécile Désaunay, Vers la déconsommation ?, in Constructif, juin 2021 (N° 59).
[GOL] Mathilde Golla, La société de déconsommation commence à faire son chemin, Novethic.
[GUI] Valérie Guillard, La société de consommation, cours PSL Paris-Dauphine.
[IMP] impots.gouv.fr, Economie collaborative et plateformes numériques.
[JDN] JDN - Journal du Net, Consommation : définition simple.
[MAR] Margaux, Société d'hyperconsommation : comment en sommes-nous arrivés là ? Comment changer demain ?, Suricates Consulting.
[ODI] ODI - Observatoire de la Déontologie et de l'Information, L'information au coeur de la démocratie - Rapport Annuel 2017.
[RUM] Yannick Rumpala, Quelle place pour une "sobriété heureuse" ou un "hédonisme de la modération" dans un monde de consommateurs ?, in Dans L'Homme & la Société 2018/3 (n° 208), pages 223 à 248.
[TOU] La Toupie, Toupictionnaire.
[WIK1] Wikipedia, Société de consommation.

Sources relating to waste management :
[ADE3] ADEME, Déchets chiffres-clés - Edition 2023.
[MTE] Ministère de la transition écologique et de la cohésion des territoires, Traitement des déchets.
[NOT] notre-environnement, Le traitement des déchets.
[REC] Recygo, Poubelles de tri sélectif, comprendre les codes couleurs.
[SEN1] Sénat, Les nouvelles techniques de recyclage et de valorisation des déchets ménagers et des déchets industriels banals.

F3. Surveys

A survey is, by definition, a statistical method of analyzing a population based on a sample of this population.
It are mainly used for political purposes (to help with decision-making), electoral purposes (to exist in the political landscape), commercial purposes (to anticipate sales of a product or find out customer satisfaction), activist purposes (to defend a cause) or media purposes (to build audience).
The quality of the information collected depends largely on the rigor surrounding the design and completion of the survey, as well as the interpretation of results.
The important parameters of a survey are as follows :

1. Sample size
2. Representativeness of the sample
3. Clarity of the questionnaire
4. Effectiveness of the questionnaire
5. Neutrality of the questionnaire
6. Conduct of the survey
7. Analysis of results
8. Adjustment of results
9. Publication of results
10. Reliability of surveys
11. Sources

F3.1. Sample size [GUM][SER] :

Sample size is a determining factor in obtaining reliable results.
The following formula (Cochran's formula) determines the number of people (n) to question based on the margin of error (m) that can be tolerated on a proportion of responses (p).
n = σ² x p (1 - p) / m²
p is the expected proportion of responses relative to the sample size n (when p is unknown, we use p = 0.5).
m is the error margin tolerated for the proportion p, the confidence interval equal to [p - m, p + m].
NC is the confidence level (or probability) that the answers are within the error margin (m).
z is the quantile of order α/2 of the reduced centered normal distribution for a given confidence level NC = 1 - α (z = 1.96 for NC = 95 %, z = 2.58 for NC = 99 %).
With a confidence level of 95 % and an error margin of 5 %, the calculation gives : n = 384.16
With a confidence level of 99 % and an error margin of 2 %, the calculation gives : n = 4144.14
For a sufficiently reliable market study, we most often accept a confidence level of 95 % and an error margin of 5 %, which requires interviewing 400 people.

Note that the error margin only takes into account random error, that is to say the possible differences between sample and reference population due solely to random sampling [TOU]. It does not take into account all other errors (representativeness of the sample, quality of the questionnaire, conduct of the survey, analysis of the results).

F3.2. Representativeness of the sample :

The sample must be representative of the reference population if we want to extrapolate the survey results to the entire population.
- If it is a random survey carried out from a sample drawn at random from the entire population, it must be ensured that the sampling base is complete, up to date and without repetition, and containing all categories of society (origin , sex, age, profession, region, etc.) [GUM][LAL]. This is the method used for example for major surveys carried out by INSEE [TOU].
- If it is a selection survey with judicious choice (quota methods), it must be ensured that the quotas are substantially proportional to the fraction of the population represented by each category. This option is favored by polling institutes in France and applied to much smaller samples, generally 1000 or 2000 people [TOU].
- Internet surveys allow you to interview large numbers of people at low cost. However, email lists are generally not representative and 20 % of the population, not "connected to the Internet", is omitted [LAL].

F3.3. Clarity of the questionnaire :

- Indicate the total estimated time to answer the questionnaire, which should not be too long as it risks tiring the participant.
- Limit the questionnaire to 15 questions and each question to a single subject comprising 20 words maximum. For example, asking "How do you rate the quality of our product and customer service ?" leads to confusion which leads to ignoring the question.
- Avoid sensitive questions linked in particular to money, religion, intimacy, sexuality or family conflicts.
- Adapt the vocabulary to that of the population interviewed. For example, the question "France devotes around a quarter of national income to financing social protection. Do you consider this to be excessive, normal or insufficient ?" can be advantageously simplified by the question "Do you think that enough is spent on social protection ?".
- Give a definition of acronyms, technical words and little-used words.
- Do not use restrictive words such as "always", "never", "all" or "none", which prevent people from qualifying their comments and responding objectively.
- Do not ask imprecise questions, such as : "Have you been to the cinema recently ?" or "How much gasoline do you consume on average ?".
- Do not ask questions based on statements, such as : Do you agree with the statement "The police should not intervene" ?
- Do not ask questions containing superlatives or subjective adjectives, even emotionally charged or controversial, such as : "Was our customer service excellent ?" or "How amazing was your stay at our hotel ?".
- Do not ask questions containing implying words, such as : "Are you afraid of noise in your home ?" or "Are you excited to discover our new online store ?".
- Do not ask questions containing negative terms, such as : "Do you prefer not to use electrically assisted bicycles during your bike rides ?".
- Never use a double negative such as : "In your opinion, is the use of glycophate not without danger ?".

F3.4. Effectiveness of the questionnaire :

- Prefer closed questions (single choice or multiple choices, to be selected from a list of options) to open questions (collection of opinions), the latter leading to a long and difficult statistical analysis of the responses.
- For each closed question, limit the number of options, without forgetting the "Not concerned" or "Without opinion" option.
- Avoid imprecise options, such as "usually" or "often", replace with a clear concept such as "every day" or "more than twice a week".
- Avoid the single binary choice "Yes"/"No" which leads people to respond in a less thoughtful way and favors the "Yes" answer to appear more pleasant (positivity bias or tendency to acquiesce [JAC][SOU]). Instead, offer a single choice between two or more response options.
- For single choices with more than 2 options, prefer the choice with 4 balanced options, such as : "Very satisfied", "Satisfied", "Dissatisfied", "Very dissatisfied".
- For single choices with more than 2 options consisting of ranges, ensure that they are mutually exclusive, such as : "2 years or less", "3 to 5", "6 or more".
- For single choices with more than 2 options consisting of grades (1 to 4 for example), explicitly mention that grade 1 corresponds to the lowest grade.
- For multiple choices, classify them in alphabetical order, without forgetting the "Other" option.
- Add contextual information to explain and guide the participant in their responses.

F3.5. Neutrality of the questionnaire :

You should only give credit to surveys whose questions are as neutral as possible. Some questions call for answers. For example [LAL] :
- IF we ask "Do you prefer to use the old version or this improved version of the website ?", this is a biased question since the question implies by the word "improve" that the latest version of the site is best.
- If we ask "Do you think airlines should allow the use of cell phones in flight ?" the answers will not be the same as if we ask "Do you think airlines should ban cell phone use in flight ?"
- If we ask "Do you find it important that security rules at airports are tightened ?", most people will answer in the affirmative. However, if we tell them about the conditions that will accompany this greater security (longer waits, increased police presence, increased ticket costs, etc.), their opinion may be different.
- If we ask "Are you in favor or against sanctioning judges in the event of a fault leading to a judicial error ?", who would not want to sanction someone who has committed a fault ?

F3.6. Conduct of the survey :

When the survey is carried out in the "field" (face-to-face or telephone survey), it is necessary to ensure that :
- The investigators are serious, professional, well trained, neutral in appearance, welcoming and relational.
- The place, time and circumstances are propitious. For example, only launch the survey when the media context is relatively neutral in relation to the subject of the survey.
- The participant is available to answer the questionnaire.

F3.7. Analysis of results :

The understanding and interpretation of the results are sometimes very different depending on the analyst. For example [LAL] :
- If business travelers are asked "Do you often, occasionally, rarely or never use Internet access in your hotel room ?", the results will differ greatly depending on the groupings that we will provide answers. Does the "yes" result corresponding to the "often" case also include the "occasionally" case, or even the "rarely" case ?
- If the results show that "60 % of Canadians use their credit card to pay for their vacations", then the information should not be condensed into the form "Canadians travel on credit".

F3.8. Adjustment of results [DAN] :

Adjustment is a common practice in the world of surveys.
It consists of applying weightings to individuals to increase the weight of those belonging to categories under-represented in the sample surveyed compared to the reference population, and to simultaneously reduce the weight of those who are over-represented.
Adjustment on a single variable corresponds to a simple rule of 3. Adjustment on several variables at the same time is more complex and requires lengthy computer calculations.
But be careful, excessive weightings pose a certain risk to the quality of the results. Thus, it seems absurd to give 10 times more weight to the answers of the only person we managed to interview in a given category.
It is also possible that the calculations do not allow the sample questioned to converge towards the desired distribution.
Thus, if data is false from the start, if it was poorly collected, incorrectly entered, or if it contains too much missing data, there will be no point in trying to correct it.
Hence the extreme importance of ensuring that samples consistent with the reference population are obtained in advance.

F3.9. Publication of results :

Any published survey must be accompanied by certain information.
The French law of July 19, 1977 regulates surveys made public on the national territory and linked to the electoral debate. They must mention at least the purpose of the survey, the name of the organization, the name of the sponsor, the number of people questioned, the date, the exact wording of the questions asked and the proportion of "unanswered" [DOC].

F3.10. Reliability of surveys :

Concerning the reliability of the surveys, opinions are divided :
For some people, despite their faults, surveys are good indicators of trends and opinions [LAL]. They are not wrong when they are well done and observed in a trending manner.
For others, surveys reflect an opinion formed on the spot. Responding to a pollster doesn't commit you to anything. This can even be an opportunity to play, or even to express your anger at the moment.
The surveys also reflect an opinion drowned out in the media noise surrounding the question asked.
But most often, the survey is used to build audience. Its relevance is almost never mentioned.
Only in-depth surveys, repeated from year to year, are of interest in understanding changes in values over the long term [COS].

F3.11. Sources relating to surveys :

[COS] Centre d'observation de la société, Le sondage - un mauvais outil pour comprendre la société.
[DAN] Gérard Danaguezian, Le redressement d'échantillons, Survey Magazine.
[DOC] Doctrine, Loi n° 77-808 du 19 juillet 1977 relative à la publication et à la diffusion de certains sondages d'opinion.
[GUM] Hervé Gumuchian et Claude Marois, Chapitre 6 - Les méthodes d'échantillonnage et la détermination de la taille de l'échantillon, in Initiation à la recherche en géographie, Presses de l'Université de Montréal.
[JAC] Marc Jacquemain, Méthodologie de l'enquête, Institut des Sciences Humaines et Sociales, Université de Liège.
[LAL] Michèle Laliberté, L'art des sondages ou comment éviter les pièges, Réseau Veille Tourisme.
[PER] Anne Perrut, Cours de probabilités et statistiques.
[SER] Zineb Serhier, Comment calculer la taille d'un échantillon pour une étude observationnelle ?.
[SOU] Dr. Ghomari Souhila, Techniques d'Enquête, Université de Tlemcen.
[TOU] Hugo Touzet, Connaître et mesurer l'opinion publique : utilité et limites des sondages, Ressources en Sciences Economiques et Sociales.
[WIK1] Wikipedia, Intervalle de confiance.
[WIK2] Wikipedia, Marge d'erreur.
[WIK3] Wikipedia, Loi normale.

F4. Statistics

When we have a data set, for example from numerous measurements, it is often useful to characterize it by parameters of central tendency (such as the arithmetic mean or the median) and dispersion (such as the standard deviation or the interquartile range).
It is also important to know the influence of aberrant data on these parameters.
Finally, the statistical method has a certain number of traps into which even experienced users can fall.
Consider a list of n data x_i, the index i ranging from 1 to n. The most common statistical parameters are then the following :

1. Aberrant data
2. Parameters of central tendency
3. Dispersion parameters
4. Misleading statistics
5. Sources

F4.1. Aberrant data [WIK5]

Aberrant data is data that contrasts greatly with other data, in an abnormally low or high manner.
Aberrant date is due to :
- either a measurement error in which case it is necessary to delete the aberrant data or use robust statistical indicators in the face of aberrant data,
- or to a highly asymmetrical data distribution in which case one must be very careful in using tools or reasoning designed for a normal distribution.

Different methods exist to identify aberrant date present in a dataset.
The simplest [KHA] consists of classifying the data in ascending order then identifying the first quartile (Q1), the third quartile (Q3) and the interquartile range EI = Q3 - Q1.
Any data x_i verifying one of the following relationships will then be considered aberrant :
x_i < Q1 - 1,5 EI    or    x_i > Q3 + 1,5 EI

The Figure above shows an example dataset with aberrant data (shown in bold font).
The table on the right shows the influence of these aberrant data on the calculation of the various common statistical parameters for four particular cases :
   case a : set of 5 data without any aberrant data
   case b : set of 6 data including those of case a supplemented by an abnormally low data
   case c : set of 6 data including those of case a supplemented by an abnormally high data
   case d : set of 7 data including those from case a supplemented by aberrant data from cases b and c
The analysis of this table is given below for each statistical parameter.

F4.2. Parameters of central tendency

The main parameters of central tendency are as follows, including the median which is robust to aberrant data.


Generalized mean M_p [WIK2] :

For n strictly positive data x_i, the generalized mean of non-zero order p (or Hölder mean) is the quantity : M_p = ( (1/n) ∑_i[x_i^p] )^(1/p)
This mean is used in practice with :
   p → -∞ for the data minimum Min{x_i}
   p = -1 for the harmonic mean M_H
   p → 0 for the geometric mean M_G
   p = 1 for the arithmetic mean M_A
   p = 2 for the root mean square M_Q
   p → +∞ for the data maximum Max{x_i}
Between different means, we have the following relationship : Min{x_i} ≤ M_H ≤ M_G ≤ M_A ≤ M_Q ≤ Max{x_i}
The generalized mean does not depend on the order of the data.
The generalized mean is homogeneous : for any strictly positive constant k, we have the relation : M_p(k x_i) = k M_p(x_i)
The generalized mean is cumulative : if the data list is divided into several sublists, the mean of the overall list is the weighted mean of the means of the sublists, with the coefficients of each sublist being the number of terms concerned.
The generalized mean can be expressed in the form of a norm of order p :

Harmonic mean M_H [WIK1] :

For n strictly positive data x_i, the harmonic mean is the quantity : M_H = ( (1/n) ∑_i[x_i^-1] )^(-1) which can also be written : 1/M_H = (1/n) ∑_i[1/x_i]
The harmonic mean is to be used when we seek to mean a quantity which influences according to an inverse proportionality in a physical phenomenon (example : mean speed of a vehicle on journeys of the same length).
The harmonic mean minimizes the squared deviation defined by the sum ∑_i[ (1/x - 1/x_i)² ]
Example [BIB] : you take a bike ride. You start by climbing a hill of length L at speed v1 = 20 km/h, then you go back down this same hill at speed v2 = 30 km/h. What is your mean speed v ? Please note, this is not 25 km/h found by taking the arithmetic mean.
If t1 = L/v1 is the time taken to ascend and t2 = L/v2 the time to descend, then the total time t = 2 L/v is written : t = t1 + t2 = L/v1 + L/v2 , or again : 2/v = 1/v1 + 1/v2
The mean speed v is therefore the harmonic mean of the two speeds v1 and v2, i.e.: v = 24 km/h.

The M_H harmonic mean is highly sensitive to aberrant data when it is abnormally low relative to other data (see Table above).



Geometric mean M_G [WIK1] :

For n strictly positive data x_i, the geometric mean is the quantity : M_G = ( Produit_i[x_i] )^1/n which can also be written : ln[M_G] = (1/n) ( ∑_i[ ln[x_i] ] )
The geometric mean is to be used when we seek to have a balanced representation of the influence of low data and high data thanks to their logarithmic transformation.
The geometric mean minimizes the squared deviation defined by the sum ∑_i[ (ln[x] - ln[x_i])² ]
Example [BIB] : at the end of a demonstration, the police announce x₁ = 10,000 demonstrators and the organizers x₂ = 100,000. What is the real number x of demonstrators ? Please note, this is not 55,000 found by taking the arithmetic mean.
If we assume that the police and the organizers "cheat" in the same way, then the police announce (x/k) demonstrators and the organizers (x k), k being a multiplier coefficient. By taking the geometric mean, we then find the exact result : x = [(x/k) (x k)]1/2 = 31,600.

The M_H geometric mean is highly sensitive to aberrant data when they are abnormally low relative to other data (see Table above).



Arithmetic mean M_A (or "usual mean") [WIK1] :

For any n data x_i, the arithmetic mean (or "usual mean") is the quantity : M_A = (1/n) ∑_i[x_i]
The arithmetic mean minimizes the squared deviation defined by the sum ∑_i[ (x - x_i)² ]

The arithmetic mean M_A is sensitive to aberrant data (see Table above). It should only be calculated on a normal distribution or after identifying and removing aberrant data.



Root mean square M_Q [WIK1] :

For any n data x_i, the quadratic mean is the quantity : M_Q = ( (1/n) ∑_i[x_i²] )^(1/2) which can also be written : M_Q² = (1/n) ∑_i[x_i²]
The quadratic mean is to be used when we seek to mean a quantity which has a square influence in a physical phenomenon (example : mean speed of a particle involved in kinetic energy) or which includes values oscillating around zero (example : electrical signal).
The square mean minimizes the squared deviation defined by the sum ∑_i[ (x² - x_i²)² ]

The Root mean square M_q is highly sensitive to aberrant data (see Table above).



Weighted mean [WIK1] :

When the data are individually assigned coefficients m_i (called weights), positive and not all zero, the previous means each have a weighted version as follows :
- Weighted generalized mean : M_p = ( ∑_i[m_i x_i^p] / ∑_i[m_i] )^(1/p)
- Weighted harmonic mean : M_H = ∑_i[m_i] / ∑_i[m_i/x_i]
- Weighted geometric mean : M_G = ( Produit_i[x_i^m_i] )^1/∑_i[m_i])
- Weighted arithmetic mean (or barycenter) : M_A = ∑_i[m_i x_i] / ∑_i[m_i]
- Weighted quadratic mean : M_Q = ( ∑_i[m_i x_i²] / ∑_i[m_i] )^(1/2)
If the weights are of integer value, they define the number of repetitions of each data.
When all weights are equal, the weighted mean is the same as the unweighted mean.



Median Q2 [WIK4] :

For any n data x_i, the median (or second quartile) is the data Q2 located in the middle of the data x_i when classified in ascending order [WIK6] :
- If n is odd, then Q2 = x_{(1/2)(n + 1)}
- If n is even, then Q2 = (1/2)(x_n/2 + x_{(n/2 + 1)})
The median should be used when we seek to minimize, or even ignore, the influence of aberrant data.
The median minimizes the difference defined by the sum ∑_i[ |x - x_i| ]
Example : in digital image processing, the median filter reduces noise while preserving the contours of the objects in the image. The Figure above shows the example of an aberrant pixel (value 97) replaced by the median value (equal to 4) of its neighborhood made up of the eight surrounding pixels.

The Q2 median is robust to aberrant data (see Table above) and should be preferred over other means.



Weighted median [WIK9] :

When the data is individually assigned coefficients m_i (called weights), which are positive and not all zero, the median has a weighted version which is the data x_k which divides the mass of the weights in two when the data is classified in ascending order. We can also say that x_k is the data having a cumulative weight equal to half the sum of all the weights.
k is then solution of : ∑ _{i = 1, k-1} [m_i] ≤ (1/2) ∑_i[m_i]    and    ∑ _{i = k+1, n} [m_i] ≤ (1/2) ∑_i[m_i]
When two values of k satisfy the above condition (k inf and k sup), then the weighted median is : (1/2)(x_{k inf} + x_{k sup})
If the weights are of integer value, they define the number of repetitions of each data.
When all weights are equal, the weighted median is the same as the unweighted median.

F4.3. Dispersion parameters

The main dispersion parameters are as follows, including the interquartile range which is robust to aberrant data.


Scope e [WIK4] :

For any n data x_i, the scope (or amplitude) is the quantity : e = Max{x_i} - Min{x_i}.

The range e is highly sensitive to aberrant data (see Table above).



Mean deviation EM [WIK4] :

For any n data x_i, the mean deviation is the quantity : EM = (1/n) ∑_i[ |x_i - M_A| ]
where M_A is the arithmetic mean of the data x_i.
The mean deviation is to be used when trying to calculate the arithmetic mean of the absolute value of the deviations from the arithmetic mean.
The absolute value function not being differentiable is sometimes incompatible with certain analyses. To make the differences positive, we then resort to squaring and use the standard deviation.

The mean deviation EM is highly sensitive to aberrant data (see Table above).



Standard deviation σ [WIK4] :

For any n data x_i, the standard deviation is the quantity : σ = ( (1/n) ∑_i[ (x_i - M_A)² ] )^(1/2) = ( (1/n) ∑_i[ x_i²] - M_A² )^(1/2)
where M_A is the arithmetic mean of the data x_i.
The standard deviation is to be used when trying to calculate the square mean of the deviations from the arithmetic mean.
We have the relation : EM ≤ σ

The standard deviation σ is highly sensitive to aberrant data (see Table above). It should only be calculated on a normal distribution or after identifying and removing aberrant data.



Interquartile range EI [WIK4] :

For any n data x_i, the interquartile range is the quantity EI = Q3 - Q1
Q1, called lower quartile (or first quartile), is the data below which 25 % of the data x_i is found when classified in ascending order [WIK6] :
- If the rank (1/4)(n + 3) is integer, then Q1 = x_{(1/4)(n + 3)}
- If this rank ends with 0.25 then Q1 = (1/4)(3 x_inf + x_sup)
- If this rank ends with 0.50 then Q1 = (1/2)(x_inf + x_sup)
- If this rank ends with 0.75 then Q1 = (1/4)(x_inf + 3 x_sup)
Q3, called upper quartile (or third quartile), is the data below which 75 % of the data x_i is found when classified in ascending order [WIK6] :
- If the rank (1/4)(3 n + 1) is integer, then Q3 = x_{(1/4)(3 n + 1)}
- If this rank ends with 0.25 then Q3 = (1/4)(3 x_inf + x_sup)
- If this rank ends with 0.50 then Q3 = (1/2)(x_inf + x_sup)
- If this rank ends with 0.75 then Q3 = (1/4)(x_inf + 3 x_sup)
with x_inf = x_{lower integer rank} and x_sup = x_{upper integer rank}

Interquartile range EI is robust to aberrant data (see Table above) and should be preferred over scope e, mean deviation EM and standard deviation σ.

F4.4. Misleading statistics

Statistics, like any other technique, is not always handled with care, discernment and good faith.
It is the subject of traps, misleading evidence and even scams.


Misleading scale :

Some graphs are presented on a linear vertical scale not starting at zero, or logarithmic, or missing altogether. In all three cases, if we do not pay careful attention to the scale, the interpretation of the variable represented can be erroneous.


The right definition :

Statistics calculated on a variable only have meaning relative to its definition.
Example [INS][WIK8][MON][JAI] : in March 2017, the number of unemployed in mainland France was 2.7 million according to INSEE and 3.7 million according to the Pôle Emploi. Where does this gap come from ?
For INSEE, an unemployed person is officially an "unemployed active" person (i.e. aged 15 or over, unemployed, actively looking for work and available within two weeks), which excludes so-called "inactive" people ( young people under 15 ; student ; retired ; people in training ; discouraged people ; women with young children, not available quickly ; people unable to work ; etc.
For Pôle Emploi, an unemployed person is a person registered with an agency, unemployed and actively looking for work (category A).
20 % of the unemployed identified by INSEE are not registered with Pôle Emploi (people at the end of their rights, people removed for administrative reasons, etc.). Conversely, 40 % of unemployed people registered with Pôle emploi are not recorded by INSEE, often to benefit from certain measures.
The unemployment rate is then defined as the ratio between the number of unemployed and the number of active people, the number of active people being the sum of the number of employed people and the number of unemployed people.
In 2022, according to the INSEE survey, employment is distributed as follows : 68.7 % employed active, 5.3 % unemployed active (unemployed) and 26.0 % inactive [UNE], the unemployment rate being 7.2 %


Cumulative percentages :

When we combine increases and decreases in percentages, a multiplicative perception of the percentages is necessary.
Example [DEL2] : a price increases by 15 % then decreases by 6 %. What is the percentage price change ? The answer is not +9 %
You must in fact multiply the price by 1.15 then by 0.94, which gives 1.081 and corresponds to an increase of 8.1 %.
Note that the reversed operation "decrease by 6 % then increase by 15 %" gives the same result, the multiplication being commutative.


Percentage and absolute value :

A quantity can decrease in percentage each year at the same time as it increases in absolute value.
Example [DEL2] : A member of the government assures that the increase in deficit which was 15 % last year has been reduced to 14 % this year. The opposition claims on the contrary that the deficit which was 15 billion euros last year has increased again this year by more than a billion euros. Who is right ?
The 15 billion euros of last year's deficit corresponds to 15 % of the initial deficit (from two years ago). This was therefore 100 billion euros. Last year, the deficit increased from 100 billion to 115 billion. If, as the first statement indicates, the increase in deficit was 14 %, this year the increase therefore reached 14 % of 115 billion, or 16.1 billion. This is consistent with the second statement that the deficit increased by more than a billion. The two statements are perfectly compatible.


The aberrant mean :

The arithmetic mean has little meaning when the data distribution is unbalanced.
Example [DAN] : in a company of 200 people, 80 % of the workforce receives 1,500 euros per month and the remaining 20 % receives 10,000 euros per month. The average remuneration then amounts to 3,200 euros per month, which is an unrepresentative result when we take a simple arithmetic mean.


The hidden common cause :

Confusion is frequently made between correlation of factors (often linked by a common cause) and causality of facts (meaning cause and effect relationship).
Example 1 [ANI] : a person who has diabetes will have high blood sugar levels and feel excessive hunger. The two factors are linked and come from the same cause, which is diabetes. But high sugar levels do not cause feelings of excessive hunger, and vice versa. These are related facts but not by causality.
Example 2 [TER] : people who wear shoes larger than 45 commit three times more murders than those who wear shoes between 40 and 42. Does this mean that large shoes induce murderous behavior ? The real correlation is actually linked to gender : it turns out that homicidal behavior is found primarily in male individuals.


Law of small numbers :

The law of small numbers pushes individuals to believe that a small number of observations can accurately reflect the general population.
Example 1 [ANI] : if we count 70 % women at a meeting and we use this proportion of 70 % to guess the number of women in the world, this generalization is false because it is not representative of reality nor the randomness of the sample.
Example 2 [ANI] : it is not because we were cured using a grandmother's remedy that it really works for the entire population. This is why in medicine many tests are carried out to find out whether or not a treatment has a beneficial effect.


Paradox of the average number of children :

"Taking a family at random" and "taking a child at random" are not the same thing.
Example [DEL2] : An exhaustive survey carried out in a city indicates that families with children under 18 are distributed as follows : 10 % families with 1 child, 50 % with 2 children, 30 % with 3 children , 10 % to 4 children. The average number of children per family (among those with children) is therefore (10 + 100 + 90 + 40)/100 = 2.4.
To check this statistic, the administrative authorities carry out a survey. We survey 1,000 children under the age of 18 carefully chosen at random and ask them how many children there are in their family, including themselves. By averaging the answers, we get 2.67 ! Why is this gap so significant with the 2.4 in the statistic which took into account all families with children ?
The answer lies in the fact that by interviewing children at random, you will interview 4 times more children from families with 4 children than you will from families with 1 child, which skews the average. If there are 1000 families, there will be 100 only children, 1000 children belonging to a family of 2 children, 900 children belonging to a family of 3 children, 400 children belonging to a family of 4 children. In total, the answers given by these 2,400 children will lead to the result of 2,666... children per family.
The survey carried out does not evaluate the average number of children in a family taken at random, but the average number of children found in the family of a child taken at random.


Simpson paradox :

A phenomenon observed in several groups of data can be reversed when the groups are brought together. If we want to obtain sensible conclusions, the aggregation of results must respect certain rules of homogeneity [DEL2].
Example [WIK7][SCI][DEL1] : A patient has kidney stones. His doctor offers him two alternatives: treatment A and treatment B. To help him make his choice, the doctor informs him that a study was carried out on 700 patients. Half of them (i.e. 350) received treatment A for which there were 273 cures (i.e. 78 % of cases), and the others received treatment B for which there were 289 cures (i.e. 83 % of cases).
We also know that there are two types of calculations : small and large (see small table above).
- Treatment A is successful in 81 cases out of 87 for small stones (i.e. 93 % of cases) and in 192 cases out of 263 for large stones (i.e. 73 % of cases).
- Treatment B is successful in 234 cases out of 270 for small stones (i.e. 87 % of cases) and in 55 cases out of 80 for large stones (i.e. 69 % of cases).
In both cases (small or large stones), treatment A is more effective, while for the overall result, treatment B is more effective.
What creates the paradox, and the erroneous impression that B is more effective overall, is that treatment A was given much more often for large stones, which are more difficult to treat.
To occur, the paradox requires two conditions :
- existence of an often hidden variable (called a confounding factor) which significantly influences the final result. In this example, the size of the stones affects the likelihood of treatment success.
- heterogeneous distribution of the sample studied. Treatment A is in fact more often given to large stones and B to small ones.
In science, we carry out "randomized" experiments, which ensure a homogeneous distribution : for example, if you have kidney stones and you participate in an experiment to compare treatments, you are randomly assigned treatment A or B , without the size of the calculations influencing the decision. We thus erase the heterogeneity of distribution, and the paradox disappears : treatment A will be clearly seen as being the best [MAT].
When Simpson's paradox occurs, one of the solutions to eliminate it is to make the distribution homogeneous by modifying the numbers in each data group while retaining the percentages. In the "Small calculations" line, the ratio 81/87 can be replaced by 251.38 /270 giving the same percentage 93 %. In the "Large calculations" line, the ratio 55/80 can be replaced by 180.81 /263 giving the same percentage 69 %. The "Total" line then gives a ratio of 443.38 /533 = 83.17 % for treatment A and 414.81 /533 = 77.83 % for treatment B, which confirms that treatment A is the best.

F4.5. Sources relating to statistics :

[ANI] Animafac, Les pièges de l'utilisation des chiffres.
[BIB] Bibm@th.net, Diverses moyennes.
[CAN1] Statistique Canada, Mesures de la tendance centrale.
[CAN2] Statistique Canada, Mesures de la dispersion.
[DAN] Gérard Danaguezian, Attention, statistiques !, Survey Magazine.
[DEL1] Jean-Paul Delahaye, L'embarrassant paradoxe de Simpson, Pour la Science, n°429 de juillet 2013.
[DEL2] Jean-Paul Delahaye, Déjouer les pièges des statistiques, Pour la Science, Hors-Série n°98 de février-mars 2018.
[KHA] Khan Academy, Identification des valeurs aberrantes avec la règle 1,5 x écart interquartile
[MAT] Johan Mathieu, Le paradoxe de Simpson.
[UNE] Unédic, Comprendre le halo du chômage.
[SCI] Science étonnante, Le paradoxe de Simpson.
[TER] Marc Tertre, Pourquoi faut-il se méfier des statistiques ?, Le Club de Mediapart.
[WIK1] Wikipedia, Moyenne.
[WIK2] Wikipedia, Moyenne d'ordre p.
[WIK3] Wikipedia, Discussion : Moyenne d'ordre p.
[WIK4] Wikipedia, Indicateur de dispersion.
[WIK5] Wikipedia, Donnée aberrante.
[WIK6] Wikipedia, Quartile.
[WIK7] Wikipedia, Paradoxe de Simpson.
[WIK8] Wikipedia, Chômage en France.
[WIK9] Wikipedia, Médiane pondérée.

F5. Media violence

1. Definition
2. Human violence
3. Forms of media violence
4. Controversy
5. Results
6. Conclusions
7. Sources

F5.1. Definition :

In a society of excessive consumption, we are witnessing a commodification of the whole of society. Information becomes a commodity, subject to the laws of the market and competition, as do TV programs, cinema, film productions and the media in general.
To capture the audience in this highly competitive context, the media resort to different means such as sensationalism, controversy and sometimes even fake news.
Violence is also one of these means, giving rise to what is called media violence which is, by definition, human violence shown or suggested by the media, whether verbal, physical, sexual or psychological.

F5.2. Human violence :

The animal does not seek to kill or cause suffering. It kills to feed, reproduce or defend its territory. It is neither peaceful nor cruel and never acts excessively [GAN].
Even a cat playing with a mouse to the death is not trying to cause suffering. It is only training to hone its hunting skills.

The human being is also an animal, but an animal of excess. It is distinguished from animals by the anatomical and functional importance of its brain [GAN], in particular the neocortex devoted to thought, imagination and anticipation, which allows it to explore and exploit an increasingly extensive environment.
Since the beginning of humanity, around two million years ago, human beings have been inventive with an exploring, manipulative, conquering and aggressive side. This fundamentally creative character tears him away from nature and makes him enter into excess and transgression. He then becomes ingenious in matters of violence, torture and horror, reinforced by his primitive animality in the form of celebration, sacrifice, cruelty and warlike orgy [GAN].
Thus, the neocortex, the seat of our higher cognitive abilities, stimulates our tendency to explore and possess. Human violence results from this natural quest for expansion and control.

Today, modern man is no more violent than in the past. Wars have become increasingly deadly in the 20th century, but they are becoming rarer. Criminal violence has been on the decline since the 19th century. However, it appears worse than before because we approach criminal phenomena with different standards from those used in the past, being accustomed to increasingly broad security [GAN].
The reduction in violence is thus a massive and incontestable phenomenon. But there can be periods of relapse, setback, regression. Man is civilized but he does not change in depth. The impulses, the frustrations, the violent temptations remain [PIN].

Violence is a universal fact. Wisdom consists of accepting it rather than repressing it [GAN]. But wisdom also consists of discovering that all conflict is good as long as it reveals a truth, in particular that we are obliged to agree in order to live and that the conflict does not need to be violent for that [MIC].
Svâmiji said : "The animal is subject to nature. Man fights against nature. The wise man achieves unity with nature by accompanying it in its movement".

F5.3. Forms of media violence :

The following alphabetical list gives the main forms of media violence against human beings, ranging from simple annoyance to extreme violence.

• Advertising : imposed broadcast of loud, spectacular and exuberant advertising, composed of small choppy and dynamic sequences on the zapping principle intended to capture attention [BEN][SEN2].
• Antisocial violence : violence directed towards society in the form of revolt, contempt or indifference, which can lead to delinquency, deviance or marginality.
• Audio and visual violence : sudden increase in sound to capture attention (during advertising) ; sudden camera movements or cutting of a sequence into very short shots meant to create rhythm (in action films) ; light flashes (in video games) ; fragmented screen, scroll or poor quality sound (on television) ; pop-up (on Internet) ; etc.
• Bashing : systematic denigration of a person, a group or a country.
• Buzz : rumor created to spread quickly and on a large scale (in particular via Internet) [TOU].
• Continuous information : incessant and repeated stream of facts, images and words which does not inform but saturates the audience with a fog of images and words [RIM].
• Controversy : article, discussion or debate which reflects, in a more or less fiery, even violent, passionate manner, opposing opinions on a given topic (political, scientific, literary, religious, etc.) [TOU].
• Crual violence : violence that takes pleasure in voluntarily causing the physical or moral suffering of a person or animal (intimidation, humiliation, blackmail, mental or pathological cruelty, moral or sexual harassment, incitement to hatred, etc.).
• Digital violence (or cyberviolence) : violence exercised through an online communication solution (Internet, cell phone, smartphone, etc.) in the form of sealioning, bashing, impersonation, outing, flaming, harassement, happy slapping, cyberstalking, deliberate exclusion, etc. [WIK2].
• Discrimination : any distinction made between natural or legal persons on the basis of one of the following criteria (in French law) [MDT] :
  - Identity : origin (natal, social, ethnic, national, etc.) ; age ; last name and first name ; family status (married, single, civil partnership, divorced, separated, widowed, etc.) ; physical appearance ; place of residence ; place of bank domiciliation ; ability to express oneself in a language other than French ;
  - Sex : pregnancy status ; biological sex (female, male or intersex) ; gender identity (psycho-social sex : a-, cis-, trans-gender, non-binary, queer, etc.) ; sexual orientation (a-, bi-, hetero-, homo- or pan-sexual) ; the majority model is diadic (female or male), cisgender (gender conforming to biological sex) and heterosexual (attracted to the opposite sex) ; the minority model has the acronym LGBTQ+ (Lesbians, Gays, Bisexuals, Trans, Queer, etc.).
  - Health : state of health ; disability ; autonomy loss ; economic vulnerability ; genetic characteristics ;
  - Beliefs and way of life : belonging or not to an ethnic group, nation, so-called race or religion ; political views ; morals (life habits) ; union or mutualist activities ; normal exercise of the right to strike ;
  - Alerts : status of whistleblower or person linked to the whistleblower (alert relating to a crime, a misdemeanor, a threat or harm against the general interest, a violation of national, European or international law) ;
  - Harassment : acts suffered, refused or reported as moral harassment, sexual harassment or hazing.
  
• Domestic violence : violence perpetrated by one spouse on the other within a couple, which may be verbal, physical, sexual or psychological [WIK4].
• Excessive bureaucracy (or administrative "massive tome") : suffering and exhaustion of the user when confronting the cogs of a hypertrophied and implacable administrative machine (complexity, paperwork, administrative jargon, inability to deal with particular cases, rigidity, slowness, irrationality, indecision, etc.) leading to sometimes an inextricable imbroglio (hassle, explanatory letters, waiting messages, misunderstandings, bugs, blockages, disputes, etc.).
• Extreme violence : ultra-physical violence present in particular on the Internet and in some video games.
• Fake news : misleading information disseminated with the aim of manipulating or deceiving the public (particularly on the Internet and social networks).
• Fragmented screen : broadcast of multiple images aimed at maximizing attention, the screen can be divided (generally in vertical strips), multiple (generally with a central frame surrounded by side frames) or mosaic (dynamic set of frames which split, unlink, overlap, etc.) [MAT].
• Glorified violence : violence not only trivialized but also associated with positive values of normality, even self-fulfillment, particularly in fiction programs and video games [SEN3].
• Gratuitous violence : violence in which there is no motive for the aggression, with total disinterest in the victim [SEN3].
• Hidden violence : televised violence likely to cause anxiety without the cause being able to be identified by the viewer. It can come from framing, editing, sound accompaniment or sound effects (examples : soundtrack using a mixture of percussion, heart sounds, breathing rhythms and female moans ; juxtaposition of selected shots which each last a few seconds) [YAP].
• Hoax : false news spread as a joke or with malice (false virus alert, false solidarity chain, promise of gifts, etc.).
• Illegitimate police violence : unnecessary or exaggerated violence exercised by a police officer towards other people in the exercise of his duties, and therefore outside the legal framework [WIK8].
• Immoral violence : violence that is contrary to morality or good customs defined by society (violation of dignity, vandalism, voyeurism, exhibitionism, fetishism, masochism, sadism, pedophilia, incest, rape, etc.).
• Institutional violence : action or absence of action committed in or by an institution (administrative error, illegal act, power abuse, etc.) which causes the person unnecessary physical or psychological suffering or which hinders their further development [LOO ].
• Intense Violence : realistic scene of physical conflict which may contain scenes of blood, weapons, carnage, bodily injury or death [WIK10].
• Intellectual violence : verbal abuse by a parent or teacher, in the form of sarcasm, perfectionism, excessive authority or high expectations, which has the effect of undermining the child's self-esteem [GDC].
• Malware : malicious software (spyware, adware, ransomware, virus, worm, logic bomb, Trojan horse, etc.) whose goal is to harm a computer system.
• Media violence : violence shown or suggested by media.
• Mind-numbing violence : violence which shamelessly displays blood and hatred, with the effect of destroying all critical sense among young people and preventing the formation of curious and vigilant minds [SEN3].
• Music video : short promotional video film which illustrates a song or the work of an artist. Up to 75 % of music videos contain scenes of an explicitly sexual nature, and more than half contain scenes of violence, often directed against women [NIH].
• Obscene violence : violence that openly offends modesty, particularly in the area of sexuality (pornography, reality TV, music video, social satire, etc.).
• Perverse violence : crual or immoral violence.
• Physical violence : direct action which harms the physical integrity, bodily health, life or freedom of a person (beatings, injuries, rape, torture, kidnapping, etc.).
• Poor quality sound : unintelligible dialogues which may come from : 1. actors (mumbling, poor speech, too fast delivery, verismo), 2. sound recording (distant, noisy, distorted, cut voices, etc.), 3. automatic mixing not checked manually (dialogues drowned in music, mixed languages), 4. mixing for cinema, DVD or streaming platform not transposable for television (big differences in sound volume), 5. modern televisions with rear-facing speakers (crushed sound) [SIX][ART].
• Pop-up : unwanted element (window, sound, music or words) interrupting or polluting Internet browsing, sometimes violently when the element appears as soon as the page is loaded, or completely obstructs the page, or is difficult to close or deactivate.
• Pornography : direct, even brutal, representation of sexual and deliberately obscene scenes which has the effect, in children and adolescents, of causing emotional trauma, and in adults, of reducing sexuality to a mechanical act without relational and without emotional manifestations which are the basis of a couple's sexuality [MCC].
• Propaganda (or "intox") : organized action with a view to spreading partisan, misleading or false information on a large scale.
• Pseudo-information : information whose veracity is doubtful and often unfounded.
• Psychological violence : repeated words, gestures or attitudes degrading a person's living conditions leading to an alteration of their physical or mental health (indifference, humiliation, guilt, isolation, intimidation, prohibition, control, harassment, threats, blackmail, etc.) [WIK5].
• Reality TV : program claiming to show the reality of a psycho-social experience of a group of isolated guinea pig candidates, which has the effect, through the exhibitionism and voyeurism of the intimate [WIK7], to promote individualism with manipulation of others, sexism, humiliation by the group of the "scapegoat" individual and the exaltation of contradictory feelings [CSA].
• Rumor (or grapevine) : pseudo-information transmitted by word of mouth with all the distortions introduced by each individual.
• Scoop : broadcast of sensational and immediate information showing current events from the focused and biased angle of sensationalism.
• Scroll : continuous information banner (news of the day and news alerts) scrolling in a loop on some news channels, added to the title banner of the current images. This banner is appreciated differently by viewers ("practical" for those who watch without sound and "polluting" for others).
• Sensationalism : excitement and media hype around isolated events, dramatized in a spectacular mode no longer giving reality but the "dizziness" of reality [SEN3].
• Sex : broadcast of programs with implicit sexual content or containing coarse language, sometimes with sexual violence, which can lead to an obsession with body image, precociousness in sexual relations and violence in romantic relationships among young people [GDQ].
• Sexism : discriminatory attitude adopted against the opposite sex, mainly by men who assign themselves the best role in the couple and society, at the expense of women relegated to second place and exploited as objects of pleasure [CNR].
• Sexual violence : physical or psychological violence which manifests itself in a sexual way (abuse, assault, exploitation, mutilation, cyberviolence, etc.) [FMV].
• Social networks : websites allowing you to create social connections online with a community of friends (Facebook, Twitter, Tiktok, Instagram, Linkedln, Viadeo, etc.). Their algorithms are designed according to two biases (filters) : 1. Everyone only sees or reads what confirms their opinions, beliefs or preferences [HIL][FRI] ; 2. Content that generates the most emotion, even toxicity or insults is favored [LAP][FRI].
  Moreover 88% of photos or videos published on social networks end up distributed elsewhere, notably on pornographic sites when the photo or video is "funny" or "sexy" [RFI].
• Social satire : program which spreads preconceived ideas about families, regional inhabitants, etc., putting selected people in competition or conflict, while encouraging the viewer to make fun of them maliciously [WIK6].
• Spam : unwanted message sent electronically or by telephone (email, SMS, MMS, social networks, voice message, etc.), for commercial, advertising or malicious (fraud, malware) purposes.
• Spiritual violence : verbal, physical or psychological violence that criticizes or ridicules a person for their beliefs, forces them or prevents them from practicing a religion.
• Suggested violence : violence that are not direct but suggested by an atmosphere, a context or even by the result of the act of violence.
• Talk show : debate show whose frequent excesses are the following [PER] :
  - the search for conflict and controversy ;
  - the lack of equitable speaking time ;
  - the over-representation of certain guest profiles ;
  - the spectacularization to the detriment of the substance ;
  - the lack of verification of the facts stated.
• Talk show "brawl" : heated talk show (games of political guests, injunctions to react quickly, controversy, etc.) where everyone interrupts the floor by seeking to challenge the other, or even insult them [GAG][RIM].
• Talk show "butchery" : unequal talk show where some guests (notably political guests) are deliberately destabilized thanks to the establishment of a mixture of genres which places them in the minority [LER].
• Talk show "cacophony" : confusing talk show (debate between leaders, chatter of experts, etc.) where everyone speaks at the same time, stating their opinion, thus preventing discussion.
• Talk show "indecency" : talk show where celebrities answer indiscreet or malicious questions from hosts and the public, exposing themselves to popular vindictiveness [WIK6].
• Talk show "manipulation" : biased talk show where the host does not remain neutral and becomes involved in the content of the debate, or even monopolizes the floor.
• Talk show "mockery" : talk show on trivial or indigent topics, where the public is led to take sides in an unreflective or mocking manner among debaters chosen to be living caricatures [WIK6].
• Talk show "pathos" : caricature-type talk show guided by unhealthy voyeurism, which consists of displaying the private lives of people (in particular their misfortunes) or a current topic (in particular poverty or misery) for ratings purposes [WIK6].
• Talk show "solicitation" : polemic-type talk show where guests are brought in to make a show.
• Talk show "trash" : perverse or vulgar talk show close to exhibitionism or voyeurism. For example, the show where couples or families come to argue, settle scores and insult each other in front of the cameras under the applause or whistles of the public [WIK6].
• Talk show "unpacking" : talk show of immodest, even exhibitionist testimony, where anonymous people come to expose intimate problems in the public place (sexual disorders, domestic violence, infidelity, psychiatric internment, etc.) [WIK6].
• Trivialized violence : violence represented on screen as not having serious consequences, even harmless, or on the contrary as being the only way out of conflict resolution.
• Verbal violence : violence expressed by words having the effect of despising, insulting, hurting or degrading the psychology of another person (insult, humiliation, threat, defamation, discrimination, etc.).
• Verismo : deliberately scrambled dialogues aimed at copying daily social reality in which exchanges are sometimes degraded, confused, indistinct and vague [BEL].
• Victimization : feeling of insecurity which is increasing, less due to the increase in petty crime (theft and damage), than to the systematic tendency of the media to show the world as violent and dangerous [SEN3][FLA]. "If the media gives us the impression of living in a more violent world than in the past, that is not what the statistics say which show a reduction in crime and armed conflicts. The time of Attila the Hun was much more violent than ours !" quotes André Mondoux, professor at Media School [BOU].
• Video game : gaming software played on a game console or computer. 64 % of video games contain intentional violence and 60 % reward players for harming a character [NIH].
• Violence against animals : animal abuse which can be active (beatings, injuries, torture, bullfighting, animal fighting, enclosure hunting, etc.) or passive (neglect).
• Violation of dignity : enslavement or reduction of the human person to an animal or an object (slavery, pimping, discrimination, indecent work or housing, insult or public defamation, etc.) [PAG].
• Violence : any conscious or unconscious aggression committed against oneself, another person, animal or group, which results in physical or psychological suffering, wounds, trauma or death.
• Zapping : program intended to offer a summary of the most significant moments of programs already broadcast on various channels and favoring the spectacular, the futile, the event without any contextualization, perspective or explanation [WIK6].

F5.4. Controversy :

Many people do not believe in the effects of media violence. There are six reasons for this [COU] :

• 1. Low capacity for introspection : Very low capacity of human beings to know how they themselves function.
• 2. Self-indulgence bias : Tendency to form a very "self-advantaging" perception of one's own abilities and to conclude that the effects of violence only affect "others" and not oneself.
• 3. Collective desensitization due to the strong social presence of media violence.
• 4; Economic interest of cultural industries designing violent products to deny the effects of violence.
• 5. Multiplicity of causes other than violent images alone, that can cause aggressive thoughts and violent behavior (biological, psychological and social factors).
• 6. "Catharsis" hypothesis according to which exposure to violent images would reduce violent acts. This hypothesis, put forward in psychoanalysis and taken up by defenders of the video game industry, has been abandoned by researchers today.

F5.5. Results :

On human being, the effects of media violence are mainly those of violent images (bloodshed, beatings, torture, killings, bombings, road accidents, suicide, rape, etc.).
On this topic, more than 50 years of scientific research shows that prolonged exposure to violent images makes people more violent, increases the fear of becoming a victim themselves and reduces the feeling of sympathy towards victims of violence in real life [COU][WIK9].

On children and adolescents, the effects of media violence are as follows [CBS] :
- From 0 to 2 years : high vulnerability to sound effects (noises and screams).
- From 2 to 7 years : vulnerability to intense, trivialized, antisocial or gratuitous violence.
- From 7 to 12 years old : vulnerability to intense, trivialized, antisocial or intellectual violence.
- From 12 to 18 years old : vulnerability to antisocial or spiritual violence.
The most harmful programs for young people are violent films, including some cartoons, and realistic television news. The greatest impact is achieved by the association of violence with erotic images [KUC].

The representation of violence has even more negative impact when [SEN4] :
- It is represented as justified or rewarded ;
- The violent protagonists are attractive or heroic ;
- The consequences for the victims are minimized ;
- The spectator is young or predisposed to aggression.

Also note [KUC] :
- The number of programs for young people, especially of good quality, seems insufficient (less than 10%), which encourages young people to watch programs for adults that are totally unsuitable for their age.
- Some boys with an aggressive character identify more easily with combative heroes whose behavior they reproduce in reality as well as in the fiction they have watched (mimetic effect).
- On American television, 20 to 25 violent acts per hour are broadcast in children's programs.
- On Canadian television, sexual relations between unmarried partners are shown 24 times more than those between spouses [NIH].

F5.6. Conclusions :

The remedy for media violence consists of finding a better balance between producers of violent images and consumers. This mainly involves the following actors [COU] :

• Public authorities, with more consumer protection.
• NGOs and consumer associations, with more awareness campaigns and impact studies.
• Media producers and cultural industries, with a certain interest in better positioning themselves as a "company respecting an ethical principle limiting the diffusion of violence".
• Schools, with more education about images aimed at preparing children to deal with the stress they may experience when faced with any image.
• Parents, with more protection of children in relation to violent images : respect signage (-10, -12, -16, -18 years), install parental controls, establish reasoned management of screen time, prohibit then explain, set an example and anticipate [CLE], encourage extracurricular sporting, artistic and creative activities in place of television use [KUC].

F5.7. Sources relating to media violence :

[ART] ARTE Radio, Prise de son : les 15 erreurs du débutant.
[BEN] Abdellatif Bensfia, "François HEINDERYCKX (2003), La malinformation. Plaidoyer pour une refondation de l'information", Communication, Vol. 23/2 | 2005, 259-265..
[BIL] Philippe Bilger, Pourquoi le son français est-il si mauvais ?.
[BOU] Marie-Claude Bourdon, Médias culture et violence.
[CBS] CBSC, Canadian Broadcast Standards Council, Classement des émissions en fonction de la violence - Guide de référence.
[CLE] CLEMI Le centre pour l'éducation aux médias et à l'information, Ecrans et violence.
[CNR] CNRTL, Centre National de Ressources Textuelles et Lexicales, Sexisme.
[COU] Courbet D. & Fourquet-Courbet M.P. (2014), "L'influence des images violentes sur les comportements et sur le sentiment d'insécurité chez les enfants et les adultes", Rapport Technique de Recherches, Université d'Aix-Marseille, Institut de Recherche en Sciences de l'Information et de la Communication IRSIC.
[CSA] CSA - Conseil supérieur de l'Audiovisuel, Réflexion sur les émissions dites "de téléréalité".
[FLA] Jean-Yves Flament, Téléréalité et idéologie.
[FMV] Fondation Marie-Vincent, Qu'est-ce que la violence sexuelle ?.
[FRI] France Inter, Algorithmes : les meilleurs amis des climatosceptiques.
[GAG] Christophe Gagne, "Un bon clash pour faire le buzz", Corela, 19-2 | 2021.
[GAN] René-François Gagnon, Cinq conceptions de la violence quotidienne, Mémoire 1999, Université Laval.
[GDC] Gouvernement du Canada, Ravaler sa douleur - Etude des liens entre l'anorexie, la boulimie et la violence contre les femmes et les filles.
[GDQ] Gouvernement du Québec, Le sexe dans les médias, Editions du Conseil du statut de la femme.
[GOU] Vincent Goulet, "Violence et médias", séances du Réseau Thématique n° 37 "Médias" du 3e congrès de l'Association Française de Sociologie, Paris, 14-17 avril 2009.
[HIL] David Hiler, Réchauffement climatique : comprendre ceux qui n'y croient pas, Le Temps.
[KUC] Corinne Kucharscki, Jean-Luc Saladin, Daniel Godefroy et Matthieu Blondet, La télévision nourrit la violence, Reporterre - Le média de l'écologie.
[LER] Pierre Leroux et Philippe Riutort, Intégrer les politiques aux divertissements.
[LOO] Joséphine Loock, Violence institutionnelle de l'administration publique.
[MAT] Philippe Mathieu, Pour une histoire et une esthétique de l'écran fragmenté au cinéma, Thèse 2010, Université de Montréal.
[MCC] Ministère de la Culture et de la Communication, La violence à la télévision.
[MDT] Ministère du travail, La protection contre les discriminations.
[MIC] Yves Michaud, La violence apprivoisée.
[NIH] NIH, National Library of Medicine, Les répercussions de l'usage des médias sur les enfants et les adolescents.
[PAG] PagesJaunes/PagesConseil/Droit/, Atteinte à la dignité.
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
[PIN] Steve Pinker, La diminution de la violence dans le monde est un phénomène massif et incontestable, Libération.
[RFI] RFI, Les ados et le sexe sur internet : attention danger!.
[RIM] Pierre Rimbert, Interdire l'information en continu ?, Le Monde diplomatique.
[SEN2] Sénat, Enfants et publicité télévisuelle.
[SEN3] Sénat, L'audiovisuel à l'ère du numérique.
[SEN4] Sénat, Violence dans les médias : quelles conséquences sur les enfants et la société ?.
[SIX] Nicolas Six, Pourquoi les dialogues sont-ils parfois aussi inaudibles dans les films et les séries ?, Le Monde.
[TOU] La Toupie, Toupictionnaire.
[TRO] Pauline Trouillard, "Atteinte à la dignité humaine et autres contenus toxiques à la télévision française : le Conseil d'Etat a t-il ouvert la boîte de Pandore ?", La Revue des droits de l'homme, 24 | 2023.
[WIK2] Wikipedia, Cyberharcèlement.
[WIK3] Wikipedia, Perversion.
[WIK4] Wikipedia, Violence conjugale.
[WIK5] Wikipedia, Violence psychologique.
[WIK6] Wikipedia, Télé poubelle.
[WIK7] Wikipedia, Téléréalité.
[WIK8] Wikipedia, Violence policière.
[WIK9] Wikipedia, Education parentale.
[WIK10] Wikipedia, Entertainment Software Rating Board.
[YAP] yapaka.be, Les images violentes ne sont pas nécessairement celles que l'on croit.

F6. Suspicious email

Email attacks, also known as phishing attacks, are becoming more and more common and more sophisticated [CYM][CYS][KEP].

1. Structure of an email
2. Receiving a suspicious email
3. Structure of a suspicious email
4. What not to do
5. What to do
6. Checkpoints to identify a spoofed email
7. Example of a normal (non-spoofed) email header
8. Sources

F6.1. Structure of an email :

An electronic mail (or "email" or "mail") is a written message transmitted via a computer network, from one electronic mailbox to one or more others, allowing almost immediate communication between a sender and one or more recipients.
Email uses protocols like SMTP for sending and POP/IMAP for receiving.

A complete email consists of several parts :

• A user header composed of :
  • From: sender's email address
  • To: recipients' email addresses
  • Cc: recipients' email addresses in carbon copy
  • Bcc: recipients' email addresses in blind carbon copy
  • Date: date and time of sending
  • Subject: subject of the message
  • Reply-To: email addresses to send replies to (Reply-To:), these addresses often being different from that of the sender.
• A technical header (or header detail) including additional information regarding message routing and security.
• The body of the message which can include text, images and attachments.

An email address has a syntax defined mainly by the RFC 5322 standard as follows [CHA][PER] :

• email address = localpart@domain
  • Example of an email address : jane.smith@company.com
  • The email address has a maximum length of 254 characters (including the "@" character).
• localpart = sender's mailbox identifier in the case of sending and recipient's mailbox identifier in the case of receiving (example : jane.smith). This mailbox is managed by a mail server associated with the domain.
  • The local part has a maximum length of 64 characters.
  • The authorized characters in the local part are all letters (A to Z, lowercase and uppercase), all numbers (0 to 9) and some special characters.
  • The authorized special characters are the following : !#$%&'*+-./=?^_`{|}~
  • The hyphen "-" is not allowed at the beginning or end in the local part (invalid examples : -jane.smith, jane.smith-).
  • The dot "." is not allowed at the beginning, end or in double succession in the local part (invalid examples : .jane.smith, jane.smith., jane..smith).
  • Most non-ASCII characters (Unicode characters beyond U+007F) can be allowed in the local part of an internationalized address, according to EAI (Email Address Internationalization) standards and with UTF-8 encoding (examples : C3 A8 for U+00E8 = "è", C3 B1 for U+00F1 = "ñ", E2 99 82 for the male symbol U+2642 = "♂"). However, their use depends on the compatibility of the servers and software concerned.
  • A sequence of characters can be surrounded by double quotes "..." to include special characters and other common characters such as space, comma or parenthesis (example : "user name"@company.com). and with Punycode encoding to be valid in the DNS system (example : xn--espaa-rta.com for the domain españa.com). However, email addresses with quotes are rarely used in practice because they pose compatibility problems with some email software.
• @ = separator character ("at" in English)
• domain = mail server identifier (example : company.com)
  • --------
  • The email address domain has a maximum length of 189 characters (taking into account the maximum lengths of the email address and its local part).
  • The email address domain can be entirely numeric but this is strongly discouraged so as not to confuse it with an IP address (invalid example : 123.456.789.0).
  • --------
  • The domain format is a sequence of at least two segments (labels) separated by a dot "." (example : sub.domain.com).
  • The domain segments follow a hierarchical order from left to right : first the Sub-domains, then the Second-Level Domain (SLD) and finally the Top-Level Domain (TLD). For example, for the address mail.google.com : mail = specific service or application, meaning "email management", google = main domain name of the service provider (Google LLC), com = nature of the domain, meaning "commercial".
  • The dot "." is not allowed at the beginning, end or in double succession in a domain (invalid examples : .company.com, company.com., company..com).
  • Each segment has a maximum length of 63 characters.
  • Each segment has as allowed characters all letters (A to Z, lowercase and uppercase), all numbers (0 to 9) and the hyphen "-".
  • The hyphen "-" is not allowed at the beginning or end of a segment (invalid examples : -company.com, company-.com, company.-com, company.com-).
  • Most non-ASCII characters can be allowed in the domain of an internationalized address, according to IDN (Internationalized Domain Names) standards and with Punycode encoding to be valid in DNS system (example : xn--espaa-rta.com for the domain españa.com). and with Punycode encoding to be valid in the DNS system (example : xn--espaa-rta.com for the domain españa.com). However, their use depends on the compatibility of the DNS servers and the email or browser software concerned.
    

F6.2. Receiving a suspicious email :

When you receive a suspicious email, there is no major risk in simply opening the email.
Depending on the recipient's email client configuration, the sender may only collect the following technical data about the recipient :
1. Email address. Example : jane.smith@company.com
2. Device type. Examples : Desktop, Mobile, Tablet
3. IP address (IP = Internet Protocol) : unique identifier assigned to each device connected to the Internet. Example (official website of the University of Burgundy : www.u-bourgogne.fr) : 194.199.107.34
4. Approximate geolocation (estimated position of the device connected to the Internet using its IP address). Example (for www.u-bourgogne.fr) : France, Bourgogne-Franche-Comté, Côte-d'Or, Dijon, approximate GPS coordinates : 47.3220°N, 5.0415°E
5. Operating system (OS). Examples : Windows 10 64-bits, macOS 11.5.2, Ubuntu Linux 64-bits, Android 13
6. Web browser type and version. Examples : Chrome 118.0.5993.88, Firefox 118.0.2
7. Web browser rendering engine. Examples : HTML engine (Blink, Gecko, Webkit), 3D engine for video games and 3D software, Engine for 3D image synthesis
8. Preferred Web browser language. Examples : fr-FR, en-US
9. Type of email client. Examples : Gmail, Outlook 365, Apple Mail
10. Date and time the email was opened. Example : 2024-10-02 14:32:22 UTC+2
This data can be used later by the cybercriminal for more targeted attacks.

F6.3. Structure of a suspicious email :

The criteria for identifying a suspicious email are as follows [CHA][PER] :
- Sender address whose local part or domain contains one of the following typical anomalies :
   - a series of random letters or numbers (examples : contact-entreprise8765@gmail.com, contact-entreprise@gmail-5g78.com
   - an inversion between two characters (notably "l" and "capital i", "l" and "1", "O" and "0"). Examples : john.d0e@example.com, help@paypaI.com, support@paypa1.com, info@micros0ft.com
   - multiple hyphens (example : help@secure-paypal-login.com)
   - a single spelling mistake that escapes attention (example : john.does@example.com, help@amazom.com)
   - an unusual domain extension, notably certain free extensions such as .tk, .ml, .ga (example : john.doe@example.tk)
- Unexpected email. Example : invoice or unordered package.
- Inconsistent email compared to the sender's usual communications :
   - at the address level. Example : email claiming to come from a bank and using a Gmail address.
   - at the format level. Examples : logo, header, colors or different layout.
   - at the content level : lack of customization. Example : "Dear customer, we have detected suspicious activity on your account. Please click here to secure it. Kind regards. The security team."
- Content with image instead of text (which prevents the email from being detected by spam filters).
- Spelling or grammatical errors. Example : "Thank you for you're trust. "
- Mention of a wonderful offer or promise of easy winnings. Example : "Congratulations. You have won a 200 euro voucher at Amazon ! Click here to claim it now."
- Request for personal or sensitive information. Example : "Please provide us with your credit card number for verification."
- Request to deactivate antivirus, firewall or any other security measure to open an attachment or visit a site.
- Insistent, urgent or threatening tone. Example : "URGENT : your account will be blocked in 24 hours if you do not respond immediately."
- Attachment with unusual format (.exe, .zip, .scr, etc.). Example : "Please open the attached urgent_bill.exe file to check your outstanding balance."
- Link pointing to a suspicious web address.

F6.4. What not to do :

- Trust completely based on the sender address alone. It can be spoofed (see Checkpoints).
- Click on a link or image
- View images that are not loaded
- Open or download an attachment
- Reply to or forward the email
- Provide personal or sensitive information (bank details, password, etc.)
- Contact the sender using information provided in the email (phone number, email, etc.)
- Ignore a warning from your email or antivirus software that the email is potentially fraudulent.

F6.5. What to do :

- Stay calm
- Take the time to check the legitimacy of the email (sender's address, format and content of the email)
- Check links without clicking on them (by hovering over them to see the real URL)
- Copy part of the email (such as the subject or key phrases) and do an Internet search to see if other people have reported this email as fraudulent
- Preserve evidence through screenshots
- Delete email
- Change the default font of the email client to clearly distinguish between an "l" and a "capital i": switch to Times New Roman, or Georgia or Verdana for example.

F6.6. Checkpoints to identify a spoofed email [CHA][PER] :

1. View the email header details, either by right-clicking on the email (without opening it and selecting "Show original" or "Show source code"), or by opening the email (and selecting the ad hoc menu).
   Examples of menus (by opening the email) : Orange (Details - Full header), Gmail (Plus, Afficher l'original), Free (Other actions - Show original), Windows Live Mail (Properties - Details).
2. Locate the following fields :
   - From : indicates the sender's email address.
   - Return-Path or envelope sender or MAIL FROM : indicates the email address to which undeliverable messages should be returned.
   - DKIM-Signature or DKIM-Filter or X-DKIM-Result (optional field) : indicates whether the message was authenticated using the DKIM (DomainKeys Identified Mail) method.
   - Received-SPF or SPF or X-Received-SPF or X-SPF (optional field) : indicates whether the message was authenticated using the SPF (Sender Policy Framework) method.
   - Received-DMARC or MARC-Filter or X-DMARC-Result (optional field) : indicates whether the message has been authenticated using the DMARC (Domain-based Message Authentication, Reporting & Conformance) method .
   - Authentication-Results or X-Authentication-Results (optional field) : gives the results of the different authentication methods performed by the different servers (intermediate servers and receiving server).
3. Compare the "Return-Path" field with the "From" field : the email addresses must be identical.
4. Compare the "DKIM-Signature" field with the "From" field : the domain indicated after "d=" in the "DKIM-Signature" field must be identical to the domain of the email (indicated after "@" in the "From" field).
5. Examine the "Received-SPF" field : the "fail" status must not appear.
6. Examine the "Received-DMARC" field : the "fail" status must not appear.
7. Examine the "Authentication-Results" field : the statuses "dkim=fail", "spf=fail" and "dmarc=fail" must not appear.

F6.7. Example of a normal (non-spoofed) email header [PER] :

From: "John Doe" <john.doe@example.com>
To: "Jane Smith <jane.smith@company.com>
Subject: Team meeting weekly
Date: Fri, 4 Oct 2024 09:45:21 +0200
Message-ID: <1234567890@mail.example.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Return-Path: <john.doe@example.com>
Received: from mail.example.com (mail.example.com [192.0.2.1])
   by inbound.company.com (Postfix) with ESMTPS id ABC123
   for <jane.smith@company.com>; Fri, 4 Oct 2024 09:45:23 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
   d=example.com; s=dkim;
   h=from:to:subject:date:message-id; bh=...snip...; b=...snip...;
Received-SPF: pass (company.com: domain of john.doe@example.com designates 192.0.2.1 as permitted sender) client-ip=192.0.2.1; envelope-from=john.doe@example.com; helo=mail.example.com;
Authentication-Results: inbound.company.com;
   dkim=pass header.i=@example.com;
   spf=pass (company.com: domain of john.doe@example.com designates 192.0.2.1 as permitted sender) smtp.mailfrom=john.doe@example.com;
   dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=example.com

F6.8. Sources relating to suspicious email :

[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[CYM] cyber-malveillance.gouv.fr, Comment reconnaître un mail de phishing ou d'hameçonnage ?
[CYS] Cyber-securite.fr, Comment savoir si j'ai ouvert un mail douteux ?
[KEP] Keeper, Pouvez-vous être piraté simplement en ouvrant un e-mail ?
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.

F7. Suspicious web address

When browsing the web, it is essential to know how to identify questionable web addresses, as clicking on a suspicious link can expose you to major risks such as theft of personal data, malware infections and online scams.

1. Structure of web address
2. Structure of suspicious web address
3. What not to do
4. What to do
5. Sources

F7.1. Structure of web address :

A web address (or URL - Uniform Resource Locator) is the unique address of a resource (web page, file, data, etc.) on the Internet.
A web address has a syntax defined mainly by the RFC 3986 standard as follows [CHA][PER] :

• web address = protocol://[user:pathword@]domain[:port][/path][?parameters][#fragment]
  • The terms in brackets are optional.
  • Example of a complete web address : https://user:password@www.example.com:443/documents/report.pdf?id=1234&lang=en#section2
  • The web address has a maximum length of about 30,000 characters (with a recommended value of about 2,000 for better readability, better processing performance on the client and web server side, and better compatibility with browsers and servers).
• protocol or scheme = protocol used to access the resource (examples : http, https, ftp, ftps, sftp, file, data, ws, wss)
• user:password = automatic authentication elements when accessing a protected web resource (example : user:password).
• domain or host = domain name or Internet Protocol (IP) address of the server hosting the resource (examples : www.example.com, example.com, blog.example.com, 192.168.1.1)
  • --------
  • The web address domain has a maximum length of 253 characters (including subdomains and the dots that separate them).
  • The web address domain can be entirely numeric (IP address) as long as it is not a special web address domain.
  • All other characteristics of an email address domain apply to a web address domain.
  • --------
  • The IPv4 address domain uses a decimal format divided into four 8-bit blocks ordered from left to right and separated by a dot "." (example : 192.168.1.1).
  • The IPv4 address domain can be followed by a space " " and a network mask. This network mask defines a range of addresses where the bits corresponding to the "1"s in the mask are fixed for the network address, while the bits corresponding to the "0"s vary from 0 to 1 to cover all addresses in the range. For example, for the address 33.0.0.0 224.0.0.0, the range is from 32.0.0.0 to 63.255.255.255. The network mask 224.0.0.0 is also written /3 in CIDR notation.
  • Some IPv4 addresses are special : the network address, which is the address whose host bits (bits corresponding to the "0" of the network mask) are at 0, and the broadcast address, which is the address whose host bits are at 1. For example, for the address 10.0.0.0 255.0.0.0, the network and broadcast addresses are respectively 10.0.0.0 and 10.255.255.255
  • --------
  • The IPv6 address domain is completely different. It uses a hexadecimal format divided into eight 16-bit blocks ordered from left to right and separated by a colon ":" (example : 2001:db8::1:0:1). A null block (0000) can be represented by a single zero. A group of consecutive null blocks can be replaced by a double colon ":", which can only be used once per address to avoid any ambiguity that a double occurrence would create. Thus, the address 2001:db8::1:0:1 expands to 2001:db8:0:0:0:1:0:1
  • The IPv6 address domain can be followed by a percentage "%" and a network zone identifier in the case of a link-local scope address (example : fe80::3%eth0).
  • The IPv6 address domain is enclosed in square brackets when used in a URL (recommended framing) or associated with a port number (mandatory framing). Examples : http://[2001:db8:a02:12f0::1]/index.html, [fe80::3%eth0]/64, [2001:db8:a02:12f0::1]:80
  • --------
  • The IPv4 or IPv6 address domain can be followed by a slash "/" and a number n according to the CIDR (Classless Inter-Domain Routing) notation. This number designates the number of bits constituting the network prefix, defining an address range where all bits located after the first n are set to 0 for the minimum address and 1 for the maximum address. For example, for the IPv4 address 33.0.0.0/3, the range is from 32.0.0.0 to 63.255.255.255. Similarly, for the IPv6 address 2001::/3, the range is from 2000:0:0:0:0:0:0:0 to 3FFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF
• port = port number that specifies the communication channel used for the connection (example : 443). By default, port 80 is used for the http host and 443 for the https host.
• path = a specific path to the resource on the server, often as a directory or file (example : documents/rapport.pdf)
  • The path has a maximum length of 253 characters. By default, the path is the root path.
• parameters = key=value pairs separated by an "&", which can be added to convey additional information about the resource (example : id=1234&lang=fr)
• fragment = a specific section of the resource, often used to navigate to a particular part of a web page (example : section2)

F7.2. Structure of suspicious web address :

The criteria for identifying a suspicious web address are as follows [CHA][PER] :
- Site with unsecured exchanges (http protocol instead of https) when it includes a personal data entry form. Note that a purely "showcase" http site is not very dangerous.
- Web address whose domain contains one of the typical anomalies of a suspicious email address
- IP address from an unsolicited email or an unknown source
- IP address used alone, without context or identification of a legitimate organization
- Special IP address that should not normally appear on the public Internet. The list of these addresses is as follows :

• Addresses not assignable to a machine (specific network functions)
  • Range used to designate an invalid, unknown or unconfigured destination
    • 0.0.0.0 - 0.255.255.255 corresponding to 0.0.0.0/8
    • 0:0:0:0:0:0:0:0 corresponding to ::/128
  • Reserved range for IPv4 addresses mapped to IPv6
    • 0:0:0:0:0:FFFF:0:0 - 0:0:0:0:0:FFFF:FFFF:FFFF corresponding to ::FFFF:0:0/96
  • Local loopback (localhost) ranges, used for internal machine communication
    • 127.0.0.0 - 127.255.255.255 corresponding to 127.0.0.0/8
    • 0:0:0:0:0:0:0:1 corresponding to ::1/128
  • Reserved range for for protocol testing
    • 192.0.0.0 - 192.0.0.255 corresponding to 192.0.0.0/24
  • Reserved ranges for specification documents and educational examples
    • 192.0.2.0 - 192.0.2.255 corresponding to 192.0.2.0/24
    • 198.51.100.0 - 198.51.100.255 corresponding to 198.51.100.0/24
    • 203.0.113.0 - 203.0.113.255 corresponding to 203.0.113.0/24
  • Multicast ranges allowing a data packet to be sent to multiple machines
    • 224.0.0.0 - 239.255.255.255 corresponding to 224.0.0.0/4
    • FF00:0:0:0:0:0:0:0 - FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF corresponding to FF00::/8
  • Limited broadcast address, used in networks local
    • 255.255.255.255 corresponding to 255.255.255.255/32
  • Ranges reserved in IPv6 for documentation or testing purposes
    • 2001:10:0:0:0:0:0:0 - 2001:10:0:0:0:0:0:FFFF corresponding to 2001:10::/24
    • 2001:DB8:0:0:0:0:0:0 - 2001:DB8:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF corresponding to 2001:DB8::/32
• Machine-assignable addresses (private or local ranges)
  • Private ranges, used in local area networks (LANs)
    • 10.0.0.0 - 10.255.255.255 corresponding to 10.0.0.0/8
    • 172.16.0.0 - 172.31.255.255 corresponding to 172.16.0.0/12
    • 192.168.0.0 - 192.168.255.255 corresponding to 192.168.0.0/16
  • Large-scale NAT or Carrier-Grade NAT (CGN) range, used by Internet Service Providers (ISPs)
    • 100.64.0.0 - 100.127.255.255 corresponding to 100.64.0.0/10
  • Automatic Private IP Addressing (APIPA) range, used when the operating system failed to obtain an IP address via DHCP
    • 169.254.0.0 - 169.254.255.255 corresponding to 169.254.0.0/16
  • Range of unique local addresses (ULA), allowing private and secure communication within local or interconnected networks
    • FC00:0:0:0:0:0:0:0:0 - FDFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF corresponding to FC00::/7
  • Link-local IPv6 address range, allowing communication between machines on the same network link without relying on external configuration or routers
    • FE80:0:0:0:0:0:0:0 - FEBF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF corresponding to FE80::/10

F7.3. What not to do :

- Click on the link.

F7.4. What to do :

- Check the owner of the IP address or domain using tools like WHOIS
- Analyze the reputation of the site via forums or specialized cybersecurity sites
- Copy the link and do an Internet search to see if other people have reported this link as fraudulent
- Preserve evidence through screenshots
- Change the default font of the email client to clearly distinguish between an "l" and a "capital i": switch to Times New Roman, or Georgia or Verdana for example.

F7.5. Sources relating to suspicious web address :

[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.

F8. Artificial intelligence

Two topics of artificial intelligence (AI) are presented below : AI engines and robotics.

1. AI engines
2. Robotics
3. Sources

F8.1. AI engines

F8.1.1. Advantages of current AI engines [CHA][PER] :

Current AI engines have some serious advantages :

• Excellent conversational assistants :
  • Ability to understand and respond in natural language
  • Fluid and contextual interaction with users
• Producers of quality summaries :
  • Ability to compile and summarize information in a coherent and systemic way
  • Neat and structured presentation of data
• Access to up-to-date information :
  • Implicit or ad hoc ability to search for up-to-date information after the date of its last learning, in order to provide relevant answers to users. This ability is not always explicitly announced.

F8.1.2. Major limitations and flaws [CHA][PER] :

The fundamental characteristics of AI engines are based on statistical and probabilistic principles that determine their operation.
But an AI engine does not "know" the real world. It simply predicts the most likely words and sentences in response to a question, without truly grasping the meaning and nuances of the real world.
Furthermore, an AI engine does not have "metacognition", being unable to reflect on its internal processes or recognize its own limitations.
These characteristics lead to major flaws and intrinsic limits in the quality of the answers provided. These include :

• 1. Invention of information ("hallucination") without warning and with persistence in error :
  • When data is hypothetical, sparse, or missing, an AI engine compensates by generating plausible text in the given context, and without warning the user.
  • Warning : Even with clear instructions to provide an answer based only on verifiable facts, an AI engine may still produce occasional hallucinations due to its probabilistic operation.
  • Concrete example : If a question is about a very sparse or poorly researched topic, the AI engine may invent details using fragments of information or extrapolate, producing an answer that, while convincing, loses all reliability.
• 2. Incorrect answer generation with persistence in the error :
  • Inconsistent data : When data is incorrect, noisy, or contradictory, an AI engine reproduces them directly in its responses without attempting to correct them.
  • Concrete example : If the AI engine encounters contradictory dates for Marie Curie's birth (for example : "November 7, 1867" and "November 12, 1867"), it can answer "November 9, 1867", choosing an intermediate value without attempting to resolve the contradiction present in the data.
  • Out-of-context data : When the question is insufficiently targeted or when the data is poorly contextualized by the AI engine, even if it is correct, the AI engine may misunderstand the context of the question or misinterpret the available data. This leads to incorrect answers.
  • Concrete example : If the question is "What are the best exercises to improve posture ?" and the AI engine answers "Running, swimming, and cycling are great for improving overall fitness." it misinterprets the question and provides out-of-context information, even if it is relevant in other contexts.
  • Data too close : When there are homonyms, close concepts, people or events that look similar, an AI engine can confuse them, for example mixing up two similar but distinct scientific theories.
  • Outdated data : An AI engine may provide outdated information in situations where updating is unavailable, insufficient or too slow, leading to errors, especially when it comes to recent events, scientific discoveries or technological developments.
  • Persistence in the error : When the user insists or rephrases a question, the AI engine can only repeat or paraphrase the initial error.
  • Error correction : If the user provides compelling evidence, such as a reliable source, a relevant excerpt, or a detailed explanation, some advanced AI engines are able to temporarily adjust their response within the same session.
• 3. Sensitivity to bias related to the non-quality of sources :
  • The training data is huge and covers very varied sources, but it is neither exhaustive nor balanced. Some information may be overrepresented, while other information is sparse, absent or biased.
  • These biases often reflect social and cultural biases present in human sources, such as discussions on online forums or news articles.
  • Consequence : An AI engine can reproduce, amplify or legitimize these biases in its responses.
• 4. Lack of contextual coherence :
  • An AI engine may have difficulty following the thread of a long discussion and connecting previously provided information, leading to inconsistencies or repetitions in its responses.
• 5. Lack of mathematical rigor and formal logic :
  • An AI engine does not perform formal logical reasoning but seeks to reproduce reasoning steps observed in its training data.
  • The user can, however, guide the AI engine toward a more rigorous proof by providing precise definitions, relevant theorems, a step-by-step logical structure for the proof, and by using mathematical symbols and notations rather than ordinary text.

F8.1.3. How to use an AI engine properly ? [CHA][PER] :

• How to choose an AI engine ?
  • To obtain targeted information, use AI engines according to their specificities. For example (in 2024) :
    • Google Search (launched by Google in September 1998) : Great for accessing a variety of sources, though it's not a conversational AI engine.
    • Perplexity (launched by Perplexity AI in December 2022) : Designed to provide synthetic, sourced answers. It's particularly useful in professional contexts where the reliability of information is paramount.
    • Microsoft Copilot (launched by Microsoft in September 2023, formerly Bing Chat) : Prized for its ultra-up-to-date answers and also useful in professional contexts. It has a higher rate of hallucinations and incorrect answers than Perplexity.
    • ChatGPT ((launched by OpenAI in November 2022) and Google Gemini (launched by Google in December 2023, formerly Bard) : Designed to provide detailed explanations. They sometimes prioritize persuasion and fluidity over truthfulness.
  • To obtain mathematical proofs, choose an AI engine that can solve mathematical problems. For example (in 2024) : Google Gemini, ChatGPT, Perplexity, Microsoft Copilot.
  • To avoid hallucinations, favor AI engines capable of minimizing hallucinations. For example (in 2024) : Perplexity, Google Gemini, Microsoft Copilot, ChatGPT.
  • To verify or deepen the answers, favor AI engines that cite their sources. For example (in 2024) : Perplexity, Google Gemini, Microsoft Copilot.
  • To benefit from continuous question and answer sessions, favor AI engines based on their maximum number of responses per session. For example (in 2024 for free versions) : Google Gemini (unlimited), Perplexity (unlimited for quick questions), ChatGPT (150 per month), Microsoft Copilot (10 per session).
  • To go back to past answers, choose an AI engine that displays the history of the interactions. For example (in 2024) : Perplexity, ChatGPT, Google Gemini.
  • To be able to correct incorrect answer, favor AI engines capable of adjusting their responses and correcting their errors based on the information provided by the user. For example (in 2024) : Perplexity, ChatGPT, Google Gemini, Microsoft Copilot.
• How to ask a question ?
  • ask only one question at a time in order to obtain a more targeted answer.
  • Ask a clear and precise question, especially to obtain a mathematical demonstration.
  • To avoid hallucinations, systematically frame the question by ending it with the sentence "Answer only with verifiable facts."
  • To avoid the AI engine becoming stubborn in erroneous or repetitive reasoning, take a break to reduce the tendency to introduce bias into questions.
• How to analyze the answer ?
  • When searching for truth, never rely on the style or fluidity of the answer.
  • Evaluate the coherence and relevance of the answers by asking the same question with different formulations.
  • Cross-check the information by comparing with other AI engines.
  • Verify crucial or unexpected information with reliable sources.
  • In sensitive or complex areas, prefer to consult human experts.
• How to get out of an inextricable situation ?
  • If an AI engine persists in erroneous or repetitive reasoning, you should switch sessions, which theoretically allows you to bypass continuity errors or biases that can accumulate during a long session.

F8.1.4. Key factors of an AI engine [CHA][PER] :

An optimal user experience of an AI engine is based on several key factors :

• Technical quality :
  • Broad indexing scope ensuring access to a vast amount of diverse and up-to-date information.
  • Careful source selection favoring quality sources while minimizing bias and misinformation.
  • Precise filtering to eliminate redundant, erroneous and unnecessary content.
  • Fast loading times to maintain user interest.
  • Intuitive and well-structured user interface designed to maximize user engagement and facilitate navigation.
  • Adherence to accessibility standards ensuring ease of use for all, including people with disabilities.
  • Respect for the confidentiality and security of personal data, both of users and data owners.
• Quality of results :
  • Excellence in conversational assistance.
  • Production of quality summaries.
  • Production of targeted information.
  • Production of exact mathematical demonstrations.
• Quality of interactions :
  • Ability to minimize hallucinations, incorrect answers and biases.
  • Contextual coherence ensuring that answers take into account the history of previous interactions.
  • Personalized interactions that automatically adapt to the user's language, adjust language and tone based on preferences, and offer relevant recommendations.

F8.2. Robotics

Modern robotics (in 2024), whether domestic or industrial, has significant advantages but remains constrained by significant dangers.
Risks related to technical or software failures, as well as uncertainties in the face of unforeseen environments, often limit the use of robots to strictly controlled spaces in order to guarantee the safety of humans.
Let's examine these aspects in more detail.

F8.2.1. Advantages of current robotics [CHA][PER] :

Current robotics has the following main advantages :

• Productivity and efficiency : Industrial robots perform repetitive tasks with speed and precision, increasing productivity in key sectors such as automotive, electronics and logistics. They minimize human error and operate without interruption or fatigue.
• Safety and risk reduction : In hazardous environments (nuclear power plants, demolition sites, laboratories handling toxic products, etc.), industrial robots replace humans, limiting their exposure to risks. Some robots, such as exoskeletons, assist workers by preventing injuries due to heavy loads.
• Advances in domestic robotics : Humanoid robots are distinguished by advanced mobility, manipulation and communication capabilities. Their design allows them to evolve in environments designed for humans, by climbing stairs, opening doors, carrying objects or handling common tools such as pens, cups or kitchen utensils.
• Contribution to science and health : Space or marine exploration robots make it possible to reach places inaccessible to humans. Surgical robots perform complex operations with precision. Companion robots play a vital role in assisting the elderly or disabled.

F8.2.2. Limits and dangers [CHA][PER] :

The main limitations and dangers of current robotics are as follows :

• High cost : Robots are still expensive to develop, manufacture, and maintain, limiting their adoption by small businesses or in developing countries.
• Technological limitations :
  • Mobility and autonomy: Humanoid robots, while promising, are often limited in terms of balance, speed, and energy endurance (insufficient batteries).
  • Fine manipulation : Compared to human dexterity, robots are still limited in tasks that require tactile sensitivity and complex coordination.
  • Environmental awareness : Even advanced AI systems (such as computer vision) can fail when faced with noisy or unforeseen environments.
  • Natural human-robot communication : Robots have difficulty understanding the nuances of language, emotions, and gestures.
• Hazards : Cohabitation between robots and their environment, particularly in warehouses and hospitals, induces risks related to the limits of their design and the unpredictability of the environments.
  • Mechanical ou electronic failures that can injure humans nearby or damage sensitive infrastructure (listed in order of decreasing frequency) :
    • 1. Breakage or wear of mechanical components causing sudden and uncontrolled movements
    • 2. Control system failure causing loss of applied force or erratic robot behavior
    • 3. Overheating of the motors or power supply causing the robot to stop suddenly or behave unpredictably
    • 4. Failure of the gripping mechanisms causing heavy or sharp objects to fall
    • 5. Failure of the brakes on the actuators preventing the robot from stopping its movements
    • 6. Rupture of high-pressure hydraulic lines causing fluid to spray
  • Software malfunctions and poor decision-making : A robot may react disproportionately, inappropriately or dangerously due to many causes (listed in order of decreasing frequency) :
    • 1. Software errors (bug in the code, bad algorithmic logic, defect in the integration of software modules, lack of robustness in the handling of exceptions)
    • 2. Poorly calibrated or faulty sensors providing incorrect data on essential parameters (distance, speed, temperature, pressure, orientation, etc.)
    • 3. Unforeseen environmental conditions (excessive noise, rain, fog, dust, inadequate lighting (insufficient or excessive), shadows, reflections, electromagnetic interference, vibrations or external shocks impacting the accuracy of the sensors or the mechanical balance)
    • 4. Insufficient training of operators to interact with the robot
    • 5. Unforeseen situations (small object not detected, partially hidden object, obstacle not identified)
    • 6. Complex scene misinterpreted (moving pedestrians, unpredictable vehicles, cluttered environment)
    • 7. Overload or insufficient system resources (processor, RAM, disk space) slowing down or blocking the calculations necessary for decision-making
    • 8. Poorly designed human-machine interaction, leading to misunderstandings or misinterpretations
    • 9. Unserious areas (absence or insufficient physical barriers, non-detection of humans in the event of a blind spot)
    • 10. Biases or limitations of artificial intelligence, leading to inappropriate or dangerous decisions
    • 11. Lack of redundancy and security in critical systems (absence of backup mechanisms in the event of a failure, weakness of emergency shutdown or recovery procedures after a serious malfunction)
    • 12. Malicious actions (hacking, injection of corrupted data, sabotage of communications)
• Social and ethical issues :
  • Impact on employment : Robotization leads to a loss of jobs for repetitive tasks, which requires retraining of workers.
  • Social acceptance : Domestic robots, particularly humanoid robots, may arouse distrust or rejection in some social groups.
  • Ethics : Domestic robots raise important questions concerning society, particularly regarding responsibilities in the event of error or harm caused.

F8.2.3. Advenir of domestic robots [CHA][PER][PET] :

Domestic robots embody a promising vision of the future where technology is put at the service of humans to improve their quality of life.
However, this vision can only be realized if technical robustness, safety and social responsibility are reconciled.
Domestic robots must not only be technically efficient and reliable, but also be thoughtfully and harmoniously integrated into our homes. This integration must take into account their social, psychological and ethical impacts.
If these complex challenges are successfully addressed, domestic robots could become essential partners in our daily lives. Otherwise, the risks and questions they raise could slow down their adoption, limiting their future to niche uses.

F8.3. Sources relating to artificial intelligence :

[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
[PET] Régis Petit, Contribution à l'intégration de la vision passive tridimensionnelle en robotique : suivi de contours, calibrage de caméra et commande cinématique de robot, Thèse de Docteur-Ingénieur, INPT Toulouse, 1985.

3. Site map

This Web site contains 65 html pages (*.htm files).
The pages translated in English are indicated in parentheses.

1. index (indexa) Accueil/Contact  (Home/Contact)
2. billard (billarda) Billard  (Billiards)
   1. bil_int (bil_inta) Théorie du jeu  (Theory of the Game)
   2. bil_pra (bil_praa) La pratique du billard  (The Art of Billiards Play)
   3. bil_liv (bil_liva) Bibliographie  (Bibliography)
   4. Arte C'est du billard, reportage ARTE
3. belier (beliera) Bélier hydraulique  (Hydraulic ram)
   1. Baillenx Pages de Hervé de Baillenx
   2. bel_pri Principe de fonctionnement
   3. bel_the Théorie
   4. bel_pra Pratique
   5. bel_ann Annexe
   6. bel_not Notations
   7. bel_glo Glossaire
   8. bel_liv (bel_liva) Bibliographie  (Bibliography)
   9. bel_som (bel_soma) Sommaire général  (Overall Table of contents)
4. snh (snha) Système Nerveux Humain  (Human Nervous System)
   1. snh_int Introduction
   2. snh_pia Piaget
   3. snh_des Description fonctionnelle
   4. snh_glo Glossaire
   5. snh_liv (snh_liva) Bibliographie  (Bibliography)
   6. snh_som (snh_soma) Sommaire général  (Overall Table of contents)
5. rel (rela) Relativité  (Relativity)
6. bot Botanique
   1. botla Liste des plantes ligneuses dont le nom commun commence par la lettre A
   2. botlb Liste des plantes ligneuses dont le nom commun commence par la lettre B
   3. botlc Liste des plantes ligneuses dont le nom commun commence par la lettre C
   4. botld Liste des plantes ligneuses dont le nom commun commence par la lettre D, E ou F
   5. botlg Liste des plantes ligneuses dont le nom commun commence par la lettre G
   6. botlh Liste des plantes ligneuses dont le nom commun commence par la lettre H, I, J, K ou L
   7. botlm Liste des plantes ligneuses dont le nom commun commence par la lettre M, N ou O
   8. botlp Liste des plantes ligneuses dont le nom commun commence par la lettre P
   9. botlq Liste des plantes ligneuses dont le nom commun commence par la lettre Q, R ou S
   10. botlt Liste des plantes ligneuses dont le nom commun commence par la lettre T, U, V, W, X, Y ou Z
7. mus Musique
8. orn Ornithologie
   1. ornla Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre A
   2. ornlb Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre B
   3. ornlc Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre C
   4. ornld Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre D, E ou F
   5. ornlg Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre G
   6. ornlh Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre H, I, J, K ou L
   7. ornlm Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre M, N ou O
   8. ornlp Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre P
   9. ornlq Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre Q, R ou S
   10. ornlt Catalogue des oiseaux d'Europe dont le nom commun commence par la lettre T, U, V, W, X, Y ou Z
9. met Météorologie
10. liens (liensa) Aide et Sujets additionnels  (Help and Additional topics)
11. liens2 (liens2a) Aide et Sujets additionnels n°2  (Help and Additional topics N°2)
12. alertea (Warning)

4. Design and Accessibility rules

At the time of last update of this page (see bottom of this page), all Web pages of this site have the following properties :
- they comply with W3C normes (HTML and CSS) ;
- they comply with Web Content Accessibility Guidelines (WCAG) 2.0 with Level AA conformance.

The design and accessibility rules of this site are as follows :

1. Web design
   1. Structuration du site en pages : selon une arborescence hiérarchique limitée à une profondeur de trois (règle des "trois clics").
   2. Version bilingue : version français/anglais de (presque) chaque page.
   3. Homogénéité des pages : même présentation et mêmes couleurs.
   4. Liens entre pages du site : depuis chaque page, accès a minima aux pages "Accueil/Contact", "Aide", ainsi qu'aux pages de type père, oncles, frères et fils.
   5. Page d'accueil : présentation simple, sur un seul écran, avec moteur de recherche interne.
2. Web ergonomy (presentation and browsing)
   1. Page : présentation structurée verticalement selon Barre de menu puis Contenu puis Pied de page, et tenant horizontalement dans l'écran.
   2. Barre de menu : avec bouton "English/Français" de type bascule.
   3. Contenu d'une page : structuration linéaire selon titre (rappel de la page père), chapitre (nom de la page courante), sommaire local (uniquement si page longue), paragraphe, sous-paragraphe, sous-sous-paragraphe...
   4. Pied de page : avec mention du copyright, année de création, nom de l'auteur et date de dernière mise à jour de la page.
   5. Liens : (presque) tous commençant par une lettre majuscule, et de couleur différente selon le type de lien (non visité, visité, survolé, activé).
   6. Liens vers fichier téléchargeable : avec indication du type de fichier (.gif, .jpeg, etc.) et de sa taille (en Ko ou Mo).
   7. Liens extra-page : avec texte court, explicite quant à la page destination.
   8. Liens intra-page : uniquement dans les pages longues.
   9. Liens "Précédent/Suivant" : uniquement entre chapitres, entre paragraphes et entre sous-paragraphes.
   10. Images porteuses d'information : avec texte alternatif (attribut "alt"), court et explicite quant à la fonction et à l'aspect.
   11. Plan de page : existe.
   12. Paragraphes : justifiés (à gauche et à droite) et indentés en première ligne.
   13. Typographie : aucun soulignement, ni texte en majuscule, et avec style "italique" uniquement dans des cas précis.
3. Accessibility to sensory handicapped
   1. Changements de langue : indiqué systématiquement (attribut "lang" dans chaque objet de type tableau, liste, bloc (balise "span"), etc.).
   2. Objets multimédias (animation, vidéo, son) : ni clignotement, défilement ou mise à jour automatique d'information, ni image animée ou à zone réactive cliquable, ni fenêtre pop-up, ni son, ni listes déroulantes, ni boîtes de dialogue. Les boutons de désactivation des animations et du son sont en effet impossibles à trouver rapidement par un non-voyant.
   3. Couleurs (utilisation) : rien ne repose uniquement sur la couleur (indication d'une action, sollicitation d'une réponse, distinction d'un élément visuel).
   4. Couleurs (standardisation) : prises parmi les 16 couleurs de base du standard HTML 4.01 (voir tableau ci-dessous, avec Nom HTML, Nom français et Code hexadécimal selon la notation #RRVVBB).
   5. Couleurs (contraste) : contraste particulièrement adapté aux daltoniens déficients en vert (soit 80 % des daltoniens, ces derniers représentant 8 % des hommes et 0,5 % des femmes), selon les règles suivantes (voir tableau ci-dessous) :
         - Arrière-plan : sans motifs ni texte (donc fond uni) ; couleur "white" pour le fond de page ; couleurs "aqua", "silver" et "white" pour les fonds de menu ; couleurs "yelow" et "red" pour les fonds de lien (respectivement survolé et activé) situés en arrière-plan par rapport au texte de lien.
         - Premier plan : couleur "black" pour le texte de page ; couleur "blue" et "purple" pour les textes de lien (respectivement non visité et visité) ; couleur "yellow" et "red" pour les fonds de lien situés en premier plan par rapport au fond de page ou de menu.
   6. Police de caractères : sans empattements, ni embellissements, ni enluminures (police sans sérif).
   7. Images : suivies si nécessaire d'un équivalent textuel expliquant le contenu de l'image.
   8. Titres : balises "h1", "h2", "h3"... logiquement enchaînées et en cohérence avec la présentation des pages en titre, chapitre, paragraphe...
   9. Tableaux : avec résumé indiquant la fonction menu/données et le nombre de colonnes (attribut "summary"), avec en-têtes de colonnes (attribut "th"), avec si nécessaire correspondance entre cellule et colonne (attributs "id" et "headers").
   10. Listes : avec numérotation systématique.
   11. Formules mathématiques : écriture littérale, y compris les fonctions mathématiques (exemple : sin[x]).
   12. Clefs d'accès des raccourcis clavier : chiffres de 0 à 9 (dont les touches couramment utilisées : 0 Aide ; 1 Accueil).

   The following table gives the contrast between each foreground color (in lines) and each background color (in rows) for the 16 basic color from HTML 4.01
   This website uses only 24 contrasts indicated by the text "OUI", especially suited to green colorblind deficient.

   Nom HTML

   black

   navy

   blue

   green

   teal

   lime

   AQUA

   maroon

   purple

   olive

   GRAY

   SILVER

   RED

   fuchsia

   YELLOW

   WHITE

   Nom français

   noir

   bleu foncé

   bleu

   vert

   bleu vert

   vert brillant

   cyan

   marron

   violet

   vert olive

   gris foncé

   gris clair

   rouge

   rose

   jaune

   blanc

   Code hexa

   000000

   000080

   0000FF

   008000

   008080

   00FF00

   00FFFF

   800000

   800080

   808000

   808080

   C0C0C0

   FF0000

   FF00FF

   FFFF00

   FFFFFF

   BLACK

   non

   non

   non

   non

   non

   non

   OUI01

   non

   non

   non

   OUI02

   OUI03

   non

   non

   non

   OUI04

   navy

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   BLUE

   non

   non

   non

   non

   non

   non

   OUI05

   non

   non

   non

   OUI06

   OUI07

   OUI08

   non

   OUI09

   OUI10

   green

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   teal

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   lime

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   aqua

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   maroon

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   PURPLE

   non

   non

   non

   non

   non

   non

   OUI11

   non

   non

   non

   OUI12

   OUI13

   OUI14

   non

   OUI15

   OUI16

   olive

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   gray

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   silver

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   RED

   non

   non

   non

   non

   non

   non

   OUI17

   non

   non

   non

   OUI18

   OUI19

   non

   non

   non

   OUI20

   fuchsia

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   YELLOW

   non

   non

   non

   non

   non

   non

   OUI21

   non

   non

   non

   OUI22

   OUI23

   non

   non

   non

   OUI24

   white

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   non

   
   
4. Html code
   1. Balises "!DOCTYPE", "html" et "head" : efficaces et en nombre restreint (pour les moteurs de recherche type Google Search).
   2. Feuille de style (.css, 3 Ko) : feuille externe unique avec attributs de taille redéfinis en relatif ("em" ou pourcentages) plutôt qu'en absolu (pixels).
   3. Balise "body" : avec attribut "bgcolor" en doublon de la feuille de style (pour compatibilité avec versions de code html inférieures à 3.2).
   4. Cadres (ou "frame") : aucun.
   5. Fenêtres secondaires : aucune.
   6. Liens javascript : aucun (hormis éventuel cassage du nom de domaine).
   7. Paragraphes : tous explicites (avec balise "p") afin de pouvoir jouer dessus avec la feuille de style.
   8. Mathematical symbols : coded in html when the code exists (examples : ≤ ∞ Δ ◊).
   9. Fichiers : nommage représentatif des deux premiers niveaux de la structure du site, sans blanc, ni caractère accentué (car problème sur serveurs Unix). Majuscules évitées au maximum.
   10. Temps d'accès aux pages : très court, avec quelques pages "pesant" au plus 100 Ko.