proposition: Lemma contains_extend2 phi psi T : phi ∈ T -> phi ∈ (T ⋄ psi).
proof: Proof. intros ?. now left. Qed.
imports: Undecidability.FOL.Syntax(Core Facts) Undecidability.Synthetic(Definitions DecidabilityFacts EnumerabilityFacts ListEnumerabilityFacts ReducibilityFacts) Undecidability(Shared.ListAutomation) Undecidability(Shared.Libs.PSL.Vectors.Vectors) Coq.Setoids.Setoid Arith Lia List