proposition: Lemma addsmx0_id m2 n (A : 'M_n) : (A + (0 : 'M_(m2, n)))%MS = A.
proof: Proof. by rewrite addsmxC adds0mx_id. 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)