proposition: Lemma rV_eqP m1 m2 n (A : 'M_(m1, n)) (B : 'M_(m2, n)) : reflect (forall u : 'rV_n, (u <= A) = (u <= B))%MS (A == B)%MS.
proof: Proof. apply: (iffP idP) => [eqAB u | eqAB]; first by rewrite (eqmxP eqAB). by apply/andP; split; apply/rV_subP=> u; rewrite 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)