English

Counterexample to Babai's lonely colour conjecture

Combinatorics 2024-10-08 v1 Discrete Mathematics Group Theory

Abstract

Motivated by colouring minimal Cayley graphs, in 1978, Babai conjectured that no-lonely-colour graphs have bounded chromatic number. We disprove this in a strong sense by constructing graphs of arbitrarily large girth and chromatic number that have a proper edge-colouring in which each cycle contains no colour exactly once.

Keywords

Cite

@article{arxiv.2410.05199,
  title  = {Counterexample to Babai's lonely colour conjecture},
  author = {James Davies and Meike Hatzel and Liana Yepremyan},
  journal= {arXiv preprint arXiv:2410.05199},
  year   = {2024}
}

Comments

11 pages, 3 figures

R2 v1 2026-06-28T19:11:36.592Z