English

Almost elusive permutation groups

Group Theory 2021-12-09 v2

Abstract

Let GG be a nontrivial transitive permutation group on a finite set Ω\Omega. An element of GG is said to be a derangement if it has no fixed points on Ω\Omega. From the orbit counting lemma, it follows that GG contains a derangement, and in fact GG contains a derangement of prime power order by a theorem of Fein, Kantor and Schacher. However, there are groups with no derangements of prime order; these are the so-called elusive groups and they have been widely studied in recent years. Extending this notion, we say that GG is almost elusive if it contains a unique conjugacy class of derangements of prime order. In this paper we first prove that every quasiprimitive almost elusive group is either almost simple or 22-transitive of affine type. We then classify all the almost elusive groups that are almost simple and primitive with socle an alternating group, a sporadic group, or a rank one group of Lie type.

Keywords

Cite

@article{arxiv.2010.02652,
  title  = {Almost elusive permutation groups},
  author = {Timothy C. Burness and Emily V. Hall},
  journal= {arXiv preprint arXiv:2010.02652},
  year   = {2021}
}

Comments

19 pages, to appear in J. Algebra