proposition: Lemma mul_mx_rowfree_eq0 (K : fieldType) (m n p: nat) (W : 'M[K]_(m,n)) (V : 'M[K]_(n,p)) : row_free V -> (W *m V == 0) = (W == 0).
proof: Proof. by move=> free; rewrite -!mxrank_eq0 mxrankMfree ?mxrank_eq0. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg ssrint div ssrnum rat poly closed_field) mathcomp(polyrcf matrix mxalgebra tuple mxpoly zmodp binomial realalg) mathcomp(mxpoly)