proposition: Lemma submxE m1 m2 n (A : 'M_(m1, n)) (B : 'M_(m2, n)) : (A <= B)%MS = (A *m cokermx B == 0).
proof: Proof. by rewrite unlock. 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)