proposition: Lemma x_mult_zero : forall x y : R, y [=] [0] -> x[*]y [=] [0].
proof: Proof. intros x y H; Step_final (x[*][0]). Qed.
imports: CoRN.tactics.CornTac CoRN.algebra.CSums CoRN.algebra.CAbMonoids Coq.Sorting.Permutation CoRN.util.SetoidPermutation Coq.Setoids.Setoid Coq.Classes.Morphisms Coq(Lia)