Ramsey numbers for multiple copies of sparse graphs
Abstract
For a graph and an integer , we let denote the disjoint union of copies of . In 1975, Burr, Erd\H{o}s, and Spencer initiated the study of Ramsey numbers for , one of few instances for which Ramsey numbers are now known precisely. They showed that there is a constant such that , provided is sufficiently large. Subsequently, Burr gave an implicit way of computing and noted that this long term behaviour occurs when is triply exponential in . Very recently, Buci\'{c} and Sudakov revived the problem and established an essentially tight bound on by showing follows this behaviour already when the number of copies is just a single exponential. We provide significantly stronger bounds on in case is a sparse graph, most notably of bounded maximum degree. These are relatable to the current state of the art bounds on and (in a way) tight. Our methods rely on a beautiful classic proof of Graham, R\"{o}dl, and Ruci\'{n}ski, with the emphasis on developing an efficient absorbing method for bounded degree graphs.
Keywords
Cite
@article{arxiv.2212.02455,
title = {Ramsey numbers for multiple copies of sparse graphs},
author = {Aurelio Sulser and Miloš Trujić},
journal= {arXiv preprint arXiv:2212.02455},
year = {2022}
}