proposition: Lemma mult_wdl : forall x1 x2 y : R, x1 [=] x2 -> x1[*]y [=] x2[*]y.
proof: Proof. intros; algebra. 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)