A polynomial bound for the number of maximal systems of imprimitivity of a finite transitive permutation group

Abstract

We show that, there exists a constant $a$ such that, for every subgroup $H$ of a finite group $G$, the number of maximal subgroups of $G$ containing $H$ is bounded above by $a|G:H{|}^{3/2}$. In particular, a transitive permutation group of degree $n$ has at most $a{n}^{3/2}$ maximal systems of imprimitivity. When $G$ is soluble, generalizing a classic result of Tim Wall, we prove a much stroger bound, that is, the number of maximal subgroups of $G$ containing $H$ is at most $|G:H|-1$.

8 pages, we answer a question of Peter Cameron on maximal systems of imprimitivity, see https://cameroncounts.wordpress.com/2016/11/28/road-closures-and-idempotent-generated-semigroups/