proposition: Lemma scalerMzr a v n : (a *: v) *~ n = a *: (v *~ n).
proof: Proof. by rewrite -!scaler_int !scalerA mulrzr mulrzl. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)