English

Precoloring extension of Vizing's Theorem for multigraphs

Combinatorics 2022-04-05 v1

Abstract

Let GG be a graph with maximum degree Δ(G)\Delta(G) and maximum multiplicity μ(G)\mu(G). Vizing and Gupta, independently, proved in the 1960s that the chromatic index of GG is at most Δ(G)+μ(G)\Delta(G)+\mu(G). The distance between two edges ee and ff in GG is the length of a shortest path connecting an endvertex of ee and an endvertex of ff. A distance-tt matching is a set of edges having pairwise distance at least tt. Edwards et al. proposed the following conjecture: For any graph GG, using the palette {1,,Δ(G)+μ(G)}\{1, \dots, \Delta(G)+\mu(G)\}, any precoloring on a distance-22 matching can be extended to a proper edge coloring of GG. Gir\~{a}o and Kang verified this conjecture for distance-99 matchings. In this paper, we improve the required distance from 99 to 33 for multigraphs GG with μ(G)2\mu(G) \ge 2.

Keywords

Cite

@article{arxiv.2204.01074,
  title  = {Precoloring extension of Vizing's Theorem for multigraphs},
  author = {Yan Cao and Guantao Chen and Guangming Jing and Xuli Qi and Songling Shan},
  journal= {arXiv preprint arXiv:2204.01074},
  year   = {2022}
}

Comments

23 pages,4 figures

R2 v1 2026-06-24T10:36:04.929Z