proposition: Lemma fs_porbitP x : CM (porbit s x) \in porbits t.
proof: Proof. Proof using. by apply (subsetP (fs_stab CM)); apply imset_f; apply imset_f. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(tuple finfun finset path bigop) mathcomp(fingroup perm action) mathcomp(ssralg matrix mxalgebra algC classfun) partition tools sorted permcomp fibered_set cycles