proposition: Lemma tensmxE {m n p q} (A : 'M_(m, n)) (B : 'M_(p, q)) i j k l : (A *t B) (mxtens_index (i, j)) (mxtens_index (k, l)) = A i k * B j l.
proof: Proof. by rewrite !mxE !mxtens_indexK. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop ssralg matrix zmodp div)