proposition: Lemma R50_inj : injective R50f.
proof: Proof. by apply: can_inj R05f _ => z; apply/eqP; case: z; do 6?case. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(choice fintype tuple finfun bigop finset fingroup) mathcomp(action perm primitive_action)