bio  website  

location  Paris France  
age  59  
visits  member for  5 years, 7 months 
seen  2 days ago  
stats  profile views  1,009 
Subjects : finite maths , combinatorics, graphs , categories.
I am problem oriented and of the geometric type.
I believe the linguisticliterary side of maths should be put forward in particular as a means to fill the gap between mathematics and general culture.
2d

comment 
How much of the ATLAS of finite groups is independently checked and/or computer verified?
This hidden reliance on ATLAS is a very interesting point of "under specification" : The software does not say in some clear and well associated documentation what is presupposed. It should say so, otherwise it is useless as is any program without specification of what it does (not how it does it).. 
Aug
15 
comment 
Mathematical software wish list
Yes the_fox you right and polite: a mathematician is neither a secretary nor a typographer. Yet he has to make up with each drudgery. Knuth is precise but does not understand the functional point of view. My taxes should be used to develop latex as a tool for maths and many disciplines, instead of being given to dubious publishers asking us to pay for articles written by researchers subsided by my very taxes (from an angry programmer). 
Jun
14 
awarded  Notable Question 
Mar
3 
comment 
A weaker concept of graph homomorphism
ATTENTION: Your nice drawing is misleading: you forgot four arrows. In fact apart from $C_3$ the three others are homeomorphic and each have an Hom towards $C_3$. 
Feb
18 
comment 
Are there other nice math books close to the style of Tristan Needham?
It certainly catches the eye and made me discover this great book ,thank you! 
Dec
10 
comment 
Lens spaces and generalized Petersen graphs
@DavidEppstein : Definition seems correct else both wickipedia and Wolfram are wrong. 
Dec
9 
comment 
Generalizations of the FourColor theorem
One basic source is: "The Fourcolor Problem: Assaults and Conquest" by Saaty and Kainen. It contains so many nice reformulations (over 120!). Could be useful to "parallel" a generalization. 
Sep
24 
awarded  Autobiographer 
Jul
21 
comment 
Theorems true but wrong.
@djechlin : Not at all : I am saying that saying $P_1$ and $P_2 \RightArrow C_1 and C_2$ is wrong when actually each $A_i$ implies $C_i$. Also asserting " $a+b$ is less than $a'+b'$" is wrong when in fact $a$ (resp. $b$) is less than $a'$ ( resp. $b'$). 
Jul
2 
awarded  Curious 
Feb
22 
comment 
Less general edge reconstruction problem for simple graphs
It couls very wel be the only example... 
Feb
8 
awarded  Nice Answer 
Feb
4 
awarded  Revival 
Jan
24 
awarded  Nice Answer 
Dec
24 
comment 
A weaker concept of graph homomorphism
I have a problem with statement 2 .If you are calling the rigid definition that for homomorphism of graphs which is classical . Then you can contract any tree to K_2 (the complete graph with 2 vertices). 
Oct
29 
awarded  Quorum 
Mar
30 
comment 
Enumerating 01 finite boxes without null rays.
@Casteels : OK you are right there was a typo the 4 and the 6 where exchanged in front of the powers ^p. 
Mar
30 
revised 
Enumerating 01 finite boxes without null rays.
Exchange coeffs. 6 and 4 inf front of 7^p and 3^p 
Mar
29 
asked  Enumerating 01 finite boxes without null rays. 
Mar
3 
revised 
Difficult examples for Frankl's unionclosed conjecture
minor 