English

Edge-colouring graphs with local list sizes

Combinatorics 2023-11-09 v2

Abstract

The famous List Colouring Conjecture from the 1970s states that for every graph GG the chromatic index of GG is equal to its list chromatic index. In 1996 in a seminal paper, Kahn proved that the List Colouring Conjecture holds asymptotically. Our main result is a local generalization of Kahn's theorem. More precisely, we show that, for a graph GG with sufficiently large maximum degree Δ\Delta and minimum degree δln25Δ\delta \geq \ln^{25} \Delta, the following holds: for every assignment of lists of colours to the edges of GG, such that L(e)(1+o(1))max{deg(u),deg(v)}|L(e)| \geq (1+o(1)) \cdot \max\left\{\rm{deg}(u),\rm{deg}(v)\right\} for each edge e=uve=uv, there is an LL-edge-colouring of GG. Furthermore, Kahn showed that the List Colouring Conjecture holds asymptotically for linear, kk-uniform hypergraphs, and recently Molloy generalized Kahn's original result to correspondence colouring as well as its hypergraph generalization. We prove local versions of all of these generalizations by showing a weighted version that simultaneously implies all of our results.

Keywords

Cite

@article{arxiv.2007.14944,
  title  = {Edge-colouring graphs with local list sizes},
  author = {Marthe Bonamy and Michelle Delcourt and Richard Lang and Luke Postle},
  journal= {arXiv preprint arXiv:2007.14944},
  year   = {2023}
}

Comments

25 pages, Accepted to JCTB

R2 v1 2026-06-23T17:29:57.048Z