proposition: Lemma pred_of_cons : forall a b n c, zero t2< a \/ zero t2< b -> pred (gcons a b n c) = match pred c with Some c' => Some (gcons a b n c') | None => None end.
proof: Proof. destruct a. - destruct b;cbn. destruct 1;lt_clean. auto. - 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)