proposition: Lemma map_mx_id (f : R -> R) : f =1 id -> forall M : 'M_(m, n), M ^ f = M.
proof: Proof. by move=> fid M; rewrite map_mx_id_in. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)