proposition: Lemma mul_rowsub_mx m n m' p f (A : 'M_(m, p)) (B : 'M_(p, n)) : rowsub f A *m B = rowsub f (A *m B) :> 'M_(m', n).
proof: Proof. by rewrite mxsub_mul mxsub_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 countalg finalg zmodp)