proposition: Lemma opair_inj x x' y y' : M_opair x y ≡' M_opair x' y' -> x ≡' x' /\ y ≡' y'.
proof: Proof. Proof using M_ZF. intros H. split. - eapply opair_inj1; eassumption. - eapply opair_inj2; eassumption. Qed.
imports: Undecidability.FOL.ZF Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Sets(ZF) Undecidability.FOL.Sets.ZF Undecidability.FOL.Reductions.PCPb_to_ZF Lia Undecidability.PCP(PCP Util.PCP_facts Reductions.PCPb_iff_dPCPb) Undecidability(Shared.ListAutomation) Morphisms