proposition: Lemma eqmx_eq0 m1 m2 n (A : 'M_(m1, n)) (B : 'M_(m2, n)) : (A :=: B)%MS -> (A == 0) = (B == 0).
proof: Proof. by move=> eqAB; rewrite -!submx0 eqAB. 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)