English

Infinite families of vertex-transitive graphs with prescribed Hamilton compression

Combinatorics 2023-05-17 v1

Abstract

Given a graph XX with a Hamilton cycle CC, the {\em compression factor κ(X,C)\kappa(X,C) of CC} is the order of the largest cyclic subgroup of Aut(C)Aut(X)\operatorname{Aut}(C)\cap\operatorname{Aut}(X), and the {\em Hamilton compression κ(X)\kappa(X) of XX } is the maximum of κ(X,C)\kappa(X,C) where CC runs over all Hamilton cycles in XX. Generalizing the well-known open problem regarding the existence of vertex-transitive graphs without Hamilton paths/cycles, it was asked by Gregor, Merino and M\"utze in [``The Hamilton compression of highly symmetric graphs'', {\em arXiv preprint} arXiv: 2205.08126v1 (2022)] whether for every positive integer kk there exists infinitely many vertex-transitive graphs (Cayley graphs) with Hamilton compression equal to kk. Since an infinite family of Cayley graphs with Hamilton compression equal to 11 was given there, the question is completely resolved in this paper in the case of Cayley graphs with a construction of Cayley graphs of semidirect products ZpZk\mathbb{Z}_p\rtimes\mathbb{Z}_k where pp is a prime and k2k \geq 2 a divisor of p1p-1. Further, infinite families of non-Cayley vertex-transitive graphs with Hamilton compression equal to 11 are given. All of these graphs being metacirculants, some additional results on Hamilton compression of metacirculants of specific orders are also given.

Keywords

Cite

@article{arxiv.2305.09465,
  title  = {Infinite families of vertex-transitive graphs with prescribed Hamilton compression},
  author = {Klavdija Kutnar and Dragan Marušič and Andriaherimanana Sarobidy Razafimahatratra},
  journal= {arXiv preprint arXiv:2305.09465},
  year   = {2023}
}

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11 pages