proposition: Lemma morphpre_invm A : invm @*^-1 A = f @* A.
proof: Proof. by rewrite morphpre_factm morphpre_idm morphimIdom. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup)