proposition: Lemma cring_mult_zero_op : forall x : R, [0][*]x [=] [0].
proof: Proof. intro x; 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)