English

The bipartite $K_{2,2}$-free process and bipartite Ramsey number $b(2, t)$

Combinatorics 2018-08-08 v1

Abstract

The bipartite Ramsey number b(s,t)b(s,t) is the smallest integer nn such that every blue-red edge coloring of Kn,nK_{n,n} contains either a blue Ks,sK_{s,s} or a red Kt,tK_{t,t}. In the bipartite K2,2K_{2,2}-free process, we begin with an empty graph on vertex set XYX\cup Y, X=Y=n|X|=|Y|=n. At each step, a random edge from X×YX\times Y is added under the restriction that no K2,2K_{2,2} is formed. This step is repeated until no more edges can be added. In this note, we analyze this process and show that the resulting graph witnesses that b(2,t)=Ω(t3/2/logt)b(2,t) =\Omega \left(t^{3/2}/\log t \right), thereby improving the best known lower bound.

Keywords

Cite

@article{arxiv.1808.02139,
  title  = {The bipartite $K_{2,2}$-free process and bipartite Ramsey number $b(2, t)$},
  author = {Deepak Bal and Patrick Bennett},
  journal= {arXiv preprint arXiv:1808.02139},
  year   = {2018}
}

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12 pages