English

Cubic factor-invariant graphs of bialternating cycle quotient type

Combinatorics 2026-01-19 v1

Abstract

In 2019, investigation of the so-called factor-invariant cubic graphs was initiated by Alspach, Khodadadpour and Kreher. For a cubic graph Γ\Gamma and a vertex-transitive subgroup GG of Aut(Γ)\mathrm{Aut}(\Gamma), a 22-factor C\mathcal{C} of Γ\Gamma is said to be {\em GG-invariant} if the set C\mathcal{C} is preserved by each element of GG. Investigations of factor-invariant cubic graphs therefore contribute to the rapidly growing theory on cubic vertex-transitive graphs, providing a better insight into the structure of such graphs. Initially, the examples where C\mathcal{C} consists of a single or just two cycles were analyzed. In a recent paper by Brian Alspach and the author of this paper, the investigation of the examples for which the corresponding quotient graph ΓC\Gamma_\mathcal{C} of Γ\Gamma with respect to C\mathcal{C} is a cycle was initiated. Moreover, the graphs of the so-called {\em alternating cycle quotient type} were classified. In this paper, the remaining examples, that is the graphs of the {\em bialternating cycle quotient type}, are classified. It is shown that they belong to a previously unknown infinite 55-parametric family of graphs of girth at most 1010 and that they are Cayley graphs of groups with respect to three involutions.

Keywords

Cite

@article{arxiv.2601.11067,
  title  = {Cubic factor-invariant graphs of bialternating cycle quotient type},
  author = {Primož Šparl},
  journal= {arXiv preprint arXiv:2601.11067},
  year   = {2026}
}

Comments

24 pages, 6 figures

R2 v1 2026-07-01T09:07:11.094Z