English

Unavoidable subgraphs in Ramsey graphs

Combinatorics 2025-02-17 v1

Abstract

We study subgraphs that appear in large Ramsey graphs for a given graph FF. The recent girth Ramsey theorem of the first two authors asserts that there are Ramsey graphs such that all small subgraphs are `forests of copies of FF' amalgamated on vertices and edges. We derive a few further consequences from this structural result and investigate to which extent such forests of copies must be present in Ramsey graphs.

Keywords

Cite

@article{arxiv.2502.09830,
  title  = {Unavoidable subgraphs in Ramsey graphs},
  author = {Christian Reiher and Vojtěch Rödl and Mathias Schacht},
  journal= {arXiv preprint arXiv:2502.09830},
  year   = {2025}
}

Comments

18 pages

R2 v1 2026-06-28T21:43:55.806Z