proposition: Lemma double_nring : forall n, Two[*]nring (R:=R) n [=] nring (R:=R) (n + n).
proof: Proof. intros. Step_final (nring (R:=R) n[+]nring n). 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)