proposition: Lemma ring_distl_minus : forall x y z : R, (y[-]z) [*]x [=] y[*]x[-]z[*]x.
proof: Proof. intros x y z. unfold cg_minus in |- *. Step_final (y[*]x[+] [--]z[*]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)