English

Immersions and Albertson's conjecture

Combinatorics 2025-10-08 v1

Abstract

A graph is said to contain KkK_k (a clique of size kk) as a weak immersion if it has kk vertices, pairwise connected by edge-disjoint paths. In 1989, Lescure and Meyniel made the following conjecture related to Hadwiger's conjecture: Every graph of chromatic number kk contains KkK_k as a weak immersion. We prove this conjecture for graphs with at most (1.64o(1))k(1.64-o(1))k vertices. As an application, we make some progress on Albertson's conjecture, according to which every graph GG with chromatic number kk satisfies cr(G)cr(Kk)cr(G) \geq cr(K_k). In particular, we show that the conjecture is true for all graphs of chromatic number kk, provided that they have at most (1.64o(1))k(1.64-o(1))k vertices.

Keywords

Cite

@article{arxiv.2510.05893,
  title  = {Immersions and Albertson's conjecture},
  author = {Jacob Fox and Janos Pach and Andrew Suk},
  journal= {arXiv preprint arXiv:2510.05893},
  year   = {2025}
}
R2 v1 2026-07-01T06:21:23.658Z