proposition: Lemma addsmx_sub m3 (C : 'M_(m3, n)) : (A + B <= C)%MS = (A <= C)%MS && (B <= C)%MS.
proof: Proof. by rewrite addsmxE col_mx_sub. 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)