Chromatic number is not tournament-local
Combinatorics
2023-12-05 v2
Abstract
Scott and Seymour conjectured the existence of a function such that, for every graph and tournament on the same vertex set, implies that for some vertex . In this note we disprove this conjecture even if is replaced by a vertex set of size . As a consequence, we answer in the negative a question of Harutyunyan, Le, Thomass\'{e}, and Wu concerning the corresponding statement where the graph is replaced by another tournament, and disprove a related conjecture of Nguyen, Scott, and Seymour. We also show that the setting where chromatic number is replaced by degeneracy exhibits a quite different behaviour.
Keywords
Cite
@article{arxiv.2305.15585,
title = {Chromatic number is not tournament-local},
author = {António Girão and Kevin Hendrey and Freddie Illingworth and Florian Lehner and Lukas Michel and Michael Savery and Raphael Steiner},
journal= {arXiv preprint arXiv:2305.15585},
year = {2023}
}
Comments
7 pages; funding information added