bio | website | |
---|---|---|
location | Paris France | |
age | 59 | |
visits | member for | 5 years, 4 months |
seen | 12 hours ago | |
stats | profile views | 991 |
Subjects : finite maths , combinatorics, graphs , categories.
I am problem oriented and of the geometric type.
I believe the linguistic-literary side of maths should be put forward in particular as a means to fill the gap between mathematics and general culture.
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 Four-Color theorem
One basic source is: "The Four-color 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 0-1 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 0-1 finite boxes without null rays.
Exchange coeffs. 6 and 4 inf front of 7^p and 3^p |
Mar 29 |
asked | Enumerating 0-1 finite boxes without null rays. |
Mar 3 |
revised |
Difficult examples for Frankl's union-closed conjecture
minor |
Mar 2 |
revised |
Difficult examples for Frankl's union-closed conjecture
Added a third point C) |
Mar 1 |
answered | Difficult examples for Frankl's union-closed conjecture |
Feb 8 |
comment |
Which finite groups are not the automorphism group of some rooted finite tree?
Thank you very much , there is still an aspect of "density". Do we loose kind of "half" when restricting to (FTAG) FiniteTree-Automorphism -Groups ? |