fact: Variable (p : X -> Prop).
imports: Undecidability.L(Computability.MuRec) Undecidability.L.Datatypes(LNat LOptions LProd) Undecidability.Synthetic(DecidabilityFacts EnumerabilityFacts ListEnumerabilityFacts ReducibilityFacts) Undecidability.L.Datatypes.List(List_basics List_nat) Datatypes