A question of Frohardt on $2$-groups, skew translation quadrangles of even order and cyclic STGQs

Abstract

We solve a fundamental question posed in Frohardt's 1988 paper [8] on finite $2$-groups with Kantor familes, by showing that finite groups $K$ with a Kantor family $(\mathcal{F},\mathcal{F}^*)$ having distinct members $A, B \in \mathcal{F}$ such that $A^* \cap B^*$ is a central subgroup of $K$ and the quotient $K/(A^* \cap B^*)$ is abelian cannot exist if the center of $K$ has exponent $4$ and the members of $\mathcal{F}$ are elementary abelian. Then we give a short geometrical proof of a recent result of Ott which says that finite skew translation quadrangles of even order $(t,t)$ (where $t$ is not a square) are always translation generalized quadrangles. This is a consequence of a complete classification of finite cyclic skew translation quadrangles of order $(t,t)$ that we carry out in the present paper.