English

Graphs with asymmetric Ramsey properties

Combinatorics 2025-11-06 v1

Abstract

Given positive integers kk and \ell we write G(Kk,K)G \rightarrow (K_k,K_\ell) if every 2-colouring of the edges of GG yields a red copy of KkK_k or a blue copy of KK_\ell and we denote by R(k)R(k) the minimum nn such that Kn(Kk,Kk)K_n\rightarrow (K_k,K_k). By using probabilistic methods and hypergraph containers we prove that for every integer k3k \geq 3, there exists a graph GG such that G(Kk,Kk)G \nrightarrow (K_k,K_k) and G(KR(k)1,Kk1)G \rightarrow (K_{R(k)-1},K_{k-1}). This result can be viewed as a variation of a classical theorem of Ne\v{s}et\v{r}il and R\"odl [The Ramsey property for graphs with forbidden complete subgraphs, Journal of Combinatorial Theory, Series B, 20 (1976), 243-249], who proved that for every integer k2k\geq 2 there exists a graph GG with no copies of KkK_k such that G(Kk1,Kk1)G\rightarrow(K_{k-1}, K_{k-1}).

Keywords

Cite

@article{arxiv.2511.02963,
  title  = {Graphs with asymmetric Ramsey properties},
  author = {Walner Mendonça and Meysam Miralaei and Guilherme O. Mota},
  journal= {arXiv preprint arXiv:2511.02963},
  year   = {2025}
}
R2 v1 2026-07-01T07:21:57.783Z