proposition: Lemma memmx_eqP m1 m2 n (R1 : 'A_(m1, n)) (R2 : 'A_(m2, n)) : reflect (forall A, (A \in R1) = (A \in R2)) (R1 == R2)%MS.
proof: Proof. apply: (iffP eqmxP) => [eqR12 A | eqR12]; first by rewrite eqR12. by apply/eqmxP/rV_eqP=> vA; rewrite -(vec_mxK vA) eqR12. 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)