English

Normal 6-edge-colorings of cubic graphs with oddness 2

Combinatorics 2025-08-29 v1

Abstract

A normal edge-coloring of a cubic graph is a proper edge-coloring, in which every edge is adjacent to edges colored with four distinct colors or to edges colored with two distinct colors. It is conjectured that 55 colors suffice for a normal edge-coloring of any bridgeless cubic graph and this statement is equivalent to the Petersen Coloring Conjecture. In this paper, we extend the result of Mazzuoccolo and Mkrtchyan (Normal 6-edge-colorings of some bridgeless cubic graphs, Discrete Appl. Math. 277 (2020), 252--262), who proved that every cycle permutation graph admits a normal edge-coloring with at most 66 colors. In particular, we show that every cubic graph with oddness 22 admits a normal edge-coloring with at most 66 colors.

Keywords

Cite

@article{arxiv.2508.20565,
  title  = {Normal 6-edge-colorings of cubic graphs with oddness 2},
  author = {Igor Fabrici and Borut Lužar and Roman Soták and Diana Švecová},
  journal= {arXiv preprint arXiv:2508.20565},
  year   = {2025}
}