proposition: Lemma enc_derivations_step B n : ZFeq' ⊢ opair (tnumeral n) (enc_stack (derivations B n)) ∈ enc_derivations B n.
proof: Proof. destruct n; cbn. - apply ZF_sing_el. - apply ZF_bunion_el. apply DI2. apply ZF_sing_el. Qed.
imports: Undecidability.FOL.ZF Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Sets.ZF Undecidability.FOL.Reductions.PCPb_to_ZF Undecidability.PCP(PCP Util.PCP_facts Reductions.PCPb_iff_dPCPb) Undecidability(Shared.ListAutomation)