proposition: Lemma genmx_muls m1 m2 n (R1 : 'A_(m1, n)) (R2 : 'A_(m2, n)) : <<(R1 * R2)%MS>>%MS = (R1 * R2)%MS.
proof: Proof. by rewrite genmx_sums; apply: eq_bigr => i; rewrite genmx_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)