English

Colouring squares of claw-free graphs

Combinatorics 2017-07-19 v3 Discrete Mathematics

Abstract

Is there some absolute ε>0\varepsilon > 0 such that for any claw-free graph GG, the chromatic number of the square of GG satisfies χ(G2)(2ε)ω(G)2\chi(G^2) \le (2-\varepsilon) \omega(G)^2, where ω(G)\omega(G) is the clique number of GG? Erd\H{o}s and Ne\v{s}et\v{r}il asked this question for the specific case of GG the line graph of a simple graph and this was answered in the affirmative by Molloy and Reed. We show that the answer to the more general question is also yes, and moreover that it essentially reduces to the original question of Erd\H{o}s and Ne\v{s}et\v{r}il.

Keywords

Cite

@article{arxiv.1609.08645,
  title  = {Colouring squares of claw-free graphs},
  author = {Rémi de Joannis de Verclos and Ross J. Kang and Lucas Pastor},
  journal= {arXiv preprint arXiv:1609.08645},
  year   = {2017}
}

Comments

19 pages; v2 corrects for a subtlety in the original derivation of Thm 1; v3 accepted to Canadian Journal of Mathematics