proposition: Lemma submx_full m1 m2 n (A : 'M_(m1, n)) (B : 'M_(m2, n)) : row_full B -> (A <= B)%MS.
proof: Proof. by rewrite submxE /cokermx => /eqnP->; rewrite /copid_mx pid_mx_1 subrr !mulmx0. 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)