On the clique number of the Paley Graph — Problem 29
On the clique number of the Paley Graph — Problem 29
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On the clique number of the Paley Graph — Problem 29
On the clique number of the Paley Graph — Problem 28
On the clique number of the Paley Graph — Problem 27
On the clique number of the Paley Graph — Problem 26
On the clique number of the Paley Graph — Problem 25
The Lovász number of random circulant graphs — Problem 18
The Lovász number of random circulant graphs — Problem 17
Let f(n) be maximal such that there is a connected graph G with n vertices and f(n) edges such that R(K 3,G)= 2n-1. Let F(n) be maximal such that every connected graph G with n vertices and $ leq F(…
For r geq 3 let d r(e) be the minimal d such that mathrm ex r(n, mathcal F )=o(n^2), where mathcal F is the family of r -uniform hypergraphs on d vertices with e edges. Prove that d r(e)=(r-…
Let G be a random graph on n vertices, in which every edge is included independently with probability 1/2 . Is there some constant C such that that chromatic number chi(G) is, almost surely, concentrated on a…
Construct a random graph on n vertices in the following way: begin with the complete graph K n . At each stage, choose uniformly a random triangle in the graph and delete all the edges of this triangle. Repeat until t…
If G is a finite graph and A,B are disjoint sets of vertices then we call A,B anticomplete if there are no edges between A and B . If t,c geq 1 then there exists d geq 1 such that if chi(G) geq d and $ o…
Let f(n) be the maximum possible chromatic number of a triangle-free graph on n vertices. Estimate f(n) .
Does every graph with chromatic number aleph 1 contain a countable subgraph which is infinitely vertex-connected?
Let G be a graph given by n points in mathbb R ^2 , where any two distinct points are at least distance 1 apart, and we draw an edge between two points if they are distance 1 apart. Let g(n) be maximal such …
Is there a constant c 0 such that every graph on 2^n vertices with minimum degree (1-c)2^n contains the n -dimensional hypercube Q n ?
Let h(n) be such that every graph on n vertices with n^2/4 many edges contains a triangle whose vertices have degrees summing to at least h(n) . Estimate h(n) . In particular, is it true that h(n) geq (2( sq…
We say that a graph is 4 -chromatic critical if it has chromatic number 4 , and removing any edge decreases the chromatic number to 3 . Is there, for arbitrarily large n , a 4 -chromatic critical graph on n verti…
Let R(k,l) be the usual Ramsey number: the smallest n such that if the edges of K n are coloured red and blue then there exists either a red K k or a blue K l . Prove the existence of some c 0 such that …
If R(k) is the Ramsey number for K k , the minimal n such that every 2 -colouring of the edges of K n contains a monochromatic copy of K k , then frac R(k) k2^ k/2 to infty.
Let f(n;r,k) be the maximal number of edges in an r -uniform hypergraph which contains no set of k many independent edges. For all r geq 3 , f(n;r,k)= max left( binom rk-1 r , binom n r - binom n-k+1 r r…
Let f(n,k) be such that every graph on n vertices and k edges can be partitioned into at most f(n,k) edge-disjoint complete graphs. Estimate f(n,k) for k n^2/4 .
Let h(n) be minimal such that there is a graph on n vertices with n+h(n) edges which contains a cycle on k vertices, for all 3 leq k leq n . Estimate h(n) . In particular, is it true that h(n) geq log 2n+…
Let h 3(k) be the minimal n such that there exists a triangle-free graph on n vertices with chromatic number k . Find an asymptotic for h 3(k) , and also prove lim k to infty frac h 3(k+1) h 3(k) =1.
Let f r(n) be minimal such that every graph on n vertices with geq f r(n) edges and chromatic number geq r contains a triangle. Determine f r(n) .