proposition: Lemma contains_extend1 phi T : phi ∈ (T ⋄ phi).
proof: Proof. now right. 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