English

Bounds for Gallai-Ramsey functions and numbers

Combinatorics 2023-01-31 v2

Abstract

For two graphs G,HG,H and a positive integer kk, the \emph{Gallai-Ramsey number} grk(G,H)\operatorname{gr}_k(G,H) is defined as the minimum number of vertices nn such that any kk-edge-coloring of KnK_n contains either a rainbow (all different colored) copy of GG or a monochromatic copy of HH. If GG and HH are both complete graphs, then we call it Gallai-Ramsey function. Fox and Sudakov proved grk(Ks,Kt)s4kt\operatorname{gr}_k(K_s,K_t)\leq s^{4kt}. Alon et al. showed that grk(Ks,Kt)(2s3+4s2)kt\operatorname{gr}_k(K_s,K_t)\leq (2s^3+4s^2)^{kt}. In this paper, we prove that grk(Ks,Kt)2kts3kt\operatorname{gr}_k(K_s,K_t)\leq 2^{kt}s^{3kt} for t47t\geq 47. We also give better upper bounds for grk(G,H)\operatorname{gr}_k(G,H) when G,HG,H are some special graphs. In this paper, we derive some lower bounds for Gallai-Ramsey functions and numbers by Lov\'{a}sz Local Lemma.

Keywords

Cite

@article{arxiv.2007.04895,
  title  = {Bounds for Gallai-Ramsey functions and numbers},
  author = {Zhao Wang and Yaping Mao and Ran Gu and Suping Cui and Hengzhe Li},
  journal= {arXiv preprint arXiv:2007.04895},
  year   = {2023}
}

Comments

17 pages

R2 v1 2026-06-23T16:59:24.255Z