proposition: Lemma ZF_numeral n : ZFeq' ⊢ tnumeral n ∈ ω.
proof: Proof. induction n; cbn. - eapply CE1. apply Ctx. firstorder. - eapply IE; try apply IHn. change (ZFeq' ⊢ ($0 ∈ ω → σ ($0) ∈ ω)[(tnumeral n)..]). apply AllE. eapply CE2. apply Ctx. firstorder. 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)