proposition: Lemma enc_stack_el B s t : (s, t) el B -> M_enc_card s t ∈ M_enc_stack B.
proof: Proof. Proof using M_ZF VIEQ. induction B as [|[u b] B IH]; cbn; auto. intros [H|H]; apply binunion_el. - right. apply sing_el. congruence. - left. apply IH, H. Qed.
imports: Undecidability.FOL.ZF Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Sets.ZF Lia Undecidability.PCP(PCP Util.PCP_facts Reductions.PCPb_iff_dPCPb) Undecidability(Shared.ListAutomation)