A construction for a counterexample to the pseudo 2-factor isomorphic graph conjecture
Abstract
A graph admiting a -factor is \textit{pseudo -factor isomorphic} if the parity of the number of cycles in all its -factors is the same. In [M. Abreu, A.A. Diwan, B. Jackson, D. Labbate and J. Sheehan. Pseudo -factor isomorphic regular bipartite graphs. Journal of Combinatorial Theory, Series B, 98(2) (2008), 432-444.] some of the authors of this note gave a partial characterisation of pseudo -factor isomorphic bipartite cubic graphs and conjectured that , the Heawood graph and the Pappus graph are the only essentially -edge-connected ones. In [J. Goedgebeur. A counterexample to the pseudo -factor isomorphic graph conjecture. Discr. Applied Math., 193 (2015), 57-60.] Jan Goedgebeur computationally found a graph on vertices which is pseudo -factor isomorphic cubic and bipartite, essentially -edge-connected and cyclically -edge-connected, thus refuting the above conjecture. In this note, we describe how such a graph can be constructed from the Heawood graph and the generalised Petersen graph , which are the Levi graphs of the Fano configuration and the M\"obius-Kantor configuration, respectively. Such a description of allows us to understand its automorphism group, which has order , using both a geometrical and a graph theoretical approach simultaneously. Moreover we illustrate the uniqueness of this graph.
Cite
@article{arxiv.2207.10961,
title = {A construction for a counterexample to the pseudo 2-factor isomorphic graph conjecture},
author = {M. Abreu and M. Funk and D. Labbate and F. Romaniello},
journal= {arXiv preprint arXiv:2207.10961},
year = {2022}
}