proposition: Lemma center_mx_sub m n (R : 'A_(m, n)) : ('Z(R) <= R)%MS.
proof: Proof. exact: capmxSl. 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 finalg zmodp matrix)