English

The asymptotic $\chi$-boundedness of hereditary families

Combinatorics 2025-06-03 v1

Abstract

A family F{\cal F} of graphs is asymptotically χ\chi-bounded with bounding function ff if almost every graph GG in the family satisfies χ(G)f(ω(G))\chi(G) \le f(\omega(G)). A graph is HH-free if it does not contain HH as an induced subgraph. We ask which hereditary families are asymptotically χ\chi-bounded, and discuss some related questions. We show that for every tree TT, almost all TT-free graphs GG satisfy χ(G)=ω(G)\chi(G)=\omega(G). We show that for every cycle CkC_k except C6C_6, almost every CkC_k-free graph GG satisfies χ(G)=ω(G)\chi(G) = \omega(G). We show that the C6C_6-free graphs are asymptotically χ\chi-bounded with bounding function f(w)=(1+o(1))w2logwf(w)=(1+o(1))\frac{w^2}{\log w}.

Keywords

Cite

@article{arxiv.2506.01070,
  title  = {The asymptotic $\chi$-boundedness of hereditary families},
  author = {Bruce Reed and Yelena Yuditsky},
  journal= {arXiv preprint arXiv:2506.01070},
  year   = {2025}
}