An Erdős-Ko-Rado theorem for finite 2-transitive groups

Abstract

We prove an analogue of the classical Erdős-Ko-Rado theorem for intersecting sets of permutations in finite 2-transitive groups. Given a finite group G acting faithfully and 2-transitively on the set X, we show that an intersecting set of maximal size in G has cardinality |G|/|X|. This generalises and gives a unifying proof of some similar recent results in the literature.