proposition: Lemma map_copid_mx n r : (copid_mx r)^f = copid_mx r :> 'M_n.
proof: Proof. by rewrite map_mxB map_mx1 map_pid_mx. 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)