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This tag is used if a reference is needed in a paper or textbook on a specific result.

6 votes
Accepted

Is there a permutation invariant for graphs?

You are essentially asking about the graph isomorphism problem. Or, more precisely, you are asking about canonical representation of graphs. There is a huge literature about this. See https://en.wikip …
Sean Eberhard's user avatar
22 votes
Accepted

A rather curious identity on sums over triple binomial terms

Just playing around with it: The RHS multiplied by $n$ is the same as $$2 \sum_{k=0}^{n-1} \binom{n+1}{k} \binom{n}{k} \binom{n+1}{k+2}.$$ Subtracting this from $n$ times the LHS gives $$\sum_{k=0}^{n …
Sean Eberhard's user avatar
4 votes
Accepted

A variation of closed-subgroup theorem

See Tao's book on Hilbert's fifth problem -- https://terrytao.wordpress.com/books/hilberts-fifth-problem-and-related-topics/ -- Theorem 3.1.7, where it is referred to as local Cartan's theorem.
Sean Eberhard's user avatar
1 vote

Partitions of ${\rm Sym}(\mathbb{N})$ induced by convergent, but not absolutely convergent s...

Is it true that if $G$ has full spectrum with respect to a series $\sum_{n=1}^\infty a_n$ then $G$ has full spectrum also with respect to any other conditionally convergent series $\sum_{n=1}^\inft …
Sean Eberhard's user avatar
2 votes

Maximum number of triangles no two of which have a common edge

I think the answer to your question "do we have some good estimates for $f(n)$?" is no. Or at least, the situation is the same as that for triangle removal itself. The assertion that $f(n) = o(n^2)$ i …
Sean Eberhard's user avatar
1 vote
Accepted

Iterative approximate solutions to games

The keywords I was looking for were "fictitious play" and "Brown--Robinson process". The short answer seems to be that it works, sometimes. For more information see https://en.wikipedia.org/wiki/Ficti …
Sean Eberhard's user avatar
3 votes
1 answer
169 views

Iterative approximate solutions to games

Suppose you and I are playing a two-player zero-sum game repeatedly. There is a payoff matrix $(A_{ij})$, and if I play action $i$ and you play action $j$ then I receive $A_{ij}$ and you receive $-A_{ …
3 votes

Powers of finite simple groups

I have no reference for this problem, but let's at least write down the trivial bounds. Let $s_1,\dots s_r\in S^n$ and suppose $n>|S|^r$. Associate to each index $i$ the element $$(\pi_i(s_1),\dots,\ …
Sean Eberhard's user avatar
9 votes

Covering a set with geometric progressions

We can reduce Lucia's upper bound of $3/8$ a little further as follows. Begin by taking the $n/4$ geometric progressions of common ratio $2$ beginning at each odd number at most $n/2$. Then for each o …
Sean Eberhard's user avatar
1 vote

Theory of cones

Grunbaum, convex polytopes: http://books.google.co.uk/books?id=ISHO86XJ1CsC&printsec=frontcover#v=onepage&q&f=false
Sean Eberhard's user avatar