English

Non-conflicting no-where zero $Z_2\times Z_2$ flows in cubic graphs

Combinatorics 2025-04-29 v1 Discrete Mathematics

Abstract

Let Z2×Z2={0,α,β,α+β}Z_2\times Z_2=\{0, \alpha, \beta, \alpha+\beta\}. If GG is a bridgeless cubic graph, FF is a perfect matching of GG and F\overline{F} is the complementary 2-factor of FF, then a no-where zero Z2×Z2Z_2\times Z_2-flow θ\theta of G/FG/\overline{F} is called non-conflicting with respect to F\overline{F}, if F\overline{F} contains no edge e=uve=uv, such that uu is incident to an edge with θ\theta-value α\alpha and vv is incident to an edge with θ\theta-value β\beta. In this paper, we demonstrate the usefulness of non-conflicting flows by showing that if a cubic graph GG admits such a flow with respect to some perfect matching FF, then GG admits a normal 6-edge-coloring. We use this observation in order to show that claw-free bridgeless cubic graphs, bridgeless cubic graphs possessing a 2-factor having at most two cycles admit a normal 6-edge-coloring. We demonstrate the usefulness of non-conflicting flows further by relating them to a recent conjecture of Thomassen about edge-disjoint perfect matchings in highly connected regular graphs. In the end of the paper, we construct infinitely many 2-edge-connected cubic graphs such that G/FG/\overline{F} does not admit a non-conflicting no-where zero Z2×Z2Z_2\times Z_2-flow with respect to any perfect matching FF.

Keywords

Cite

@article{arxiv.2410.04389,
  title  = {Non-conflicting no-where zero $Z_2\times Z_2$ flows in cubic graphs},
  author = {Vahan Mkrtchyan},
  journal= {arXiv preprint arXiv:2410.04389},
  year   = {2025}
}

Comments

19 pages, 9 figures