proposition: Lemma M_combinations_step B C : M_combinations B (M_enc_stack C) (M_enc_stack (derivation_step B C)).
proof: Proof. Proof using VIEQ M_ZF. induction B as [|[s t] B IH]; cbn; trivial. exists (M_enc_stack (derivation_step B C)), (M_enc_stack (append_all C (s, t))). rewrite M_enc_stack_app. split; trivial. split; trivial. apply comb_rel_rep. 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)