Extensions of $p$-local finite groups

Abstract

A $p$-local finite group consists of a finite $p$-group $S$, together with a pair of categories which encode “conjugacy” relations among subgroups of $S$, and which are modelled on the fusion in a Sylow $p$-subgroup of a finite group. It contains enough information to define a classifying space which has many of the same properties as $p$-completed classifying spaces of finite groups. In this paper, we study and classify extensions of $p$-local finite groups, and also compute the fundamental group of the classifying space of a $p$-local finite group.