English

A bounded diameter strengthening of K\H{o}nig's Theorem

Combinatorics 2025-04-03 v2

Abstract

K\H onig's theorem says that the vertex cover number of every bipartite graph is at most its matching number (in fact they are equal since, trivially, the matching number is at most the vertex cover number). An equivalent formulation of K\H onig's theorem is that in every 22-colouring of the edges of a graph GG, the number of monochromatic components needed to cover the vertex set of GG is at most the independence number of GG. We prove the following strengthening of K\H onig's theorem: In every 22-colouring of the edges of a graph GG, the number of monochromatic subgraphs of bounded diameter needed to cover the vertex set of GG is at most the independence number of GG.

Keywords

Cite

@article{arxiv.2409.18250,
  title  = {A bounded diameter strengthening of K\H{o}nig's Theorem},
  author = {Louis DeBiasio and António Girão and Penny Haxell and Maya Stein},
  journal= {arXiv preprint arXiv:2409.18250},
  year   = {2025}
}

Comments

6 pages, 1 figure, minor revision in response to referee reports