English

A new lower bound for the multicolor Ramsey number $r_k(K_{2, t + 1})$

Combinatorics 2024-11-26 v2

Abstract

In this short note, we provide a new infinite family of K2,t+1K_{2, t+1}-free graphs for each prime power tt. Using these graphs, we show that it is possible to partition the edges of KnK_n into parts, such that each part is isomorphic to our K2,t+1K_{2, t+1}-free graph. This yields an improved lower bound to the multicolor Ramsey number rk(K2,t+1)r_k(K_{2, t+1}) when kk and tt are powers of the same prime. For these values of kk and tt, our coloring implies that tk2+1rk(K2,t+1)tk2+k+2. tk^2 + 1 \leq r_k(K_{2, t+1}) \leq tk^2 + k + 2. where the upper bound is due to Chung and Graham.

Keywords

Cite

@article{arxiv.2411.14364,
  title  = {A new lower bound for the multicolor Ramsey number $r_k(K_{2, t + 1})$},
  author = {Vladislav Taranchuk},
  journal= {arXiv preprint arXiv:2411.14364},
  year   = {2024}
}

Comments

Result has already been proven by Lazebnik and Mubayi