proposition: Lemma cring_inv_mult_rht : forall x y : R, [--]x[*]y [=] [--] (x[*]y).
proof: Proof. intros x y. astepl (y[*] [--]x). Step_final ( [--] (y[*]x)). 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)