proposition: Lemma imps T phi psi : T ⊢ phi → psi <-> (phi :: T) ⊢ psi.
proof: Proof. split; try apply II. intros H. apply IE with phi; auto. apply (Weak H). auto. Qed.
imports: Undecidability.Synthetic(Definitions DecidabilityFacts EnumerabilityFacts ListEnumerabilityFacts ReducibilityFacts) Undecidability(FOL.Syntax.Facts FOL.Syntax.Theories) Undecidability(Shared.ListAutomation) Lia