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  • 117 votes cast
Mar
9
comment What recent discoveries have amateur mathematicians made?
to JeffE : You mean the only positive contribution.
Jan
14
comment Not especially famous, long-open problems which anyone can understand
+1If equivalent to the original conjecture your version is definitely the proper formulation, avoiding the bias of automate theory. Thank for this.
Sep
22
comment Not especially famous, long-open problems which anyone can understand
Chvatal conjecture ( see math.illinois.edu/~dwest/regs/chvatal.html) very manichean like Union Closed conjecture.
Aug
31
comment Rearrangements that never change the value of a sum
A necessary and sufficient condition is $\| {n - f(n) } \| $ is bounded. Otherwise you can makeup a serie with $0$ for sum of $a_n$ and infinity for sum of $a_{f(n)}$.
Aug
26
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 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