The GAP package CRISP provides algorithms for computing subgroups of finite soluble groups related to group classes. In particular, it allows to compute F-radicals and F-injectors for Fitting classes (and Fitting sets) F, F-residuals for formations F, and X-projectors for Schunck classes X. In order to carry out these computations, the group classes F and Xmust be given by an algorithm which decides membership in the group class.
Moreover, CRISP contains algorithms for the computation of normal subgroups invariant under a prescribed set of automorphisms and belonging to a given group class. This includes an improved method to compute the set of all normal subgroups of a finite soluble group, its characteristic subgroups, and the socle and p-socles for given primes p.Author: Burkhard Höfling