English

Induced Ramsey number for a star versus a fixed graph

Combinatorics 2020-02-05 v1

Abstract

For graphs G and H, let the induced Ramsey number IR(H,G) be the smallest number of vertices in a graph F such that any coloring of the edges of F in red and blue, there is either a red induced copy of H or a blue induced copy of G. In this note we consider the case when G=Sn is a star on n edges, for large n, and H is a fixed graph. We prove that (r-1)n < IR(H, Sn) < (r-1)(r-1)n + cn, for any c>0, sufficiently large n, and r denoting the chromatic number of H. The lower bound is asymptotically tight for any fixed bipartite H. The upper bound is attained up to a constant factor, for example by a clique H.

Keywords

Cite

@article{arxiv.2002.01297,
  title  = {Induced Ramsey number for a star versus a fixed graph},
  author = {Maria Axenovich and Izolda Gorgol},
  journal= {arXiv preprint arXiv:2002.01297},
  year   = {2020}
}
R2 v1 2026-06-23T13:30:45.588Z