fact: Fixpoint subsetb A P := match A with | nil => true | a :: A => my_inb P a && subsetb A P end.
imports: Undecidability.Synthetic(Definitions EnumerabilityFacts ListEnumerabilityFacts) Lia Undecidability.L(LProd LBool LNat LOptions) Undecidability.L.Datatypes.List(List_basics List_eqb List_extra List_nat) Undecidability(PCP)