fact: Definition listable X := exists L, forall x : X, In x L.
imports: Undecidability.FOL.Semantics(Tarski.FragmentFacts) Undecidability.FOL.Syntax(Facts) Undecidability.Synthetic.DecidabilityFacts Undecidability.Synthetic.EnumerabilityFacts Undecidability.Shared.Dec List