proposition: Lemma pred_of_cons' : forall a b n , zero t2< a \/ zero t2< b -> pred (gcons a b n zero) = None.
proof: Proof. intros a b n H; rewrite (pred_of_cons n zero H). cbn;auto. Qed.
imports: Coq(Arith List Lia Compare_dec Relations Wellfounded RelationClasses) hydras(Epsilon0) hydras(More_Arith Restriction) hydras(ON_Generic) hydras(rpo.term rpo.rpo) hydras(T2) hydras(Compat815)