English

Intersection density of transitive groups with cyclic point stabilizers

Combinatorics 2022-01-27 v1

Abstract

For a permutation group GG acting on a set VV, a subset F\mathcal{F} of GG is said to be an intersecting set if for every pair of elements g,hFg,h\in \mathcal{F} there exists vVv \in V such that g(v)=h(v)g(v) = h(v). The intersection density ρ(G)\rho(G) of a transitive permutation group GG is the maximum value of the quotient F/Gv|\mathcal{F}|/|G_v| where GvG_v is a stabilizer of a point vVv\in V and F\mathcal{F} runs over all intersecting sets in GG. If GvG_v is a largest intersecting set in GG then GG is said to have the Erd\H{o}s-Ko-Rado (EKR)-property. This paper is devoted to the study of transitive permutation groups, with point stabilizers of prime order with a special emphasis given to orders 2 and 3, which do not have the EKR-property. Among other, constructions of infinite family of transitive permutation groups having point stabilizer of order 33 with intersection density 4/34/3 and of infinite families of transitive permutation groups having point stabilizer of order 33 with arbitrarily large intersection density are given.

Keywords

Cite

@article{arxiv.2201.11015,
  title  = {Intersection density of transitive groups with cyclic point stabilizers},
  author = {Ademir Hujdurović and István Kovács and Klavdija Kutnar and Dragan Marušič},
  journal= {arXiv preprint arXiv:2201.11015},
  year   = {2022}
}

Comments

14 pages

R2 v1 2026-06-24T09:03:54.842Z