English

Forbidden subgraphs in generating graphs of finite groups

Group Theory 2021-04-23 v1

Abstract

Let GG be a 22-generated group. The generating graph Γ(G)\Gamma(G) is the graph whose vertices are the elements of GG and where two vertices g1g_1 and g2g_2 are adjacent if G=g1,g2.G = \langle g_1, g_2 \rangle. This graph encodes the combinatorial structure of the distribution of generating pairs across G.G. In this paper we study some graph theoretic properties of Γ(G)\Gamma(G), with particular emphasis on those properties that can be formulated in terms of forbidden induced subgraphs. In particular we investigate when the generating graph Γ(G)\Gamma(G) is a cograph (giving a complete description when GG is soluble) and when it is perfect (giving a complete description when GG is nilpotent and proving, among the others, that Γ(Sn)\Gamma(S_n) and Γ(An)\Gamma(A_n) are perfect if and only if n4n\leq 4). Finally we prove that for a finite group GG, the properties that Γ(G)\Gamma(G) is split, chordal or C4C_4-free are equivalent.

Keywords

Cite

@article{arxiv.2104.10867,
  title  = {Forbidden subgraphs in generating graphs of finite groups},
  author = {Andrea Lucchini and Daniele Nemmi},
  journal= {arXiv preprint arXiv:2104.10867},
  year   = {2021}
}