proposition: Lemma class_supportGidr A : {in G, normalised (class_support A G)}.
proof: Proof. by move=> x Gx /=; rewrite -class_support_set1r -class_supportM rcoset_id. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)