proposition: Lemma psupports_perm_of_porbit P : [set psupport (perm_of_porbit s) | s in [set X in P | 1 < #|X| ]] = [set X in P | 1 < #|X|].
proof: Proof. Proof using. rewrite -[RHS]imset_id. apply eq_in_imset => i; rewrite inE => /andP[_ Hi]. by rewrite psupport_perm_of_porbit. 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