English

Three local actions in $6$-valent arc-transitive graphs

Combinatorics 2020-07-10 v2 Group Theory

Abstract

It is known that there are precisely three transitive permutation groups of degree 66 that admit an invariant partition with three parts of size 22 such that the kernel of the action on the parts has order 44; these groups are called A4(6)A_4(6), S4(6d)S_4(6d) and S4(6c)S_4(6c). For each L{A4(6),S4(6d),S4(6c)}L\in \{A_4(6), S_4(6d), S_4(6c)\}, we construct an infinite family of finite connected 66-valent graphs {Γn}nN\{\Gamma_n\}_{n\in \mathbb{N}} and arc-transitive groups GnAut(Γn)G_n \le \rm{Aut}(\Gamma_n) such that the permutation group induced by the action of the vertex-stabiliser (Gn)v(G_n)_v on the neighbourhood of a vertex vv is permutation isomorphic to LL, and such that (Gn)v|(G_n)_v| is exponential in V(Γn)|\rm{V}(\Gamma_n)|. These three groups were the only transitive permutation groups of degree at most 77 for which the existence of such a family was undecided. In the process, we construct an infinite family of cubic 22-arc-transitive graphs such that the dimension of the 11-eigenspace over the field of order 22 of the adjacency matrix of the graph grows linearly with the order of the graph.

Keywords

Cite

@article{arxiv.1807.04810,
  title  = {Three local actions in $6$-valent arc-transitive graphs},
  author = {Ademir Hujdurović and Primož Potočnik and Gabriel Verret},
  journal= {arXiv preprint arXiv:1807.04810},
  year   = {2020}
}

Comments

Added appendix with computer code to check one of the results

R2 v1 2026-06-23T02:59:34.031Z