proposition: Lemma M_ext x y : x ⊆ y -> y ⊆ x -> x = y.
proof: Proof. Proof using M_ZF VIEQ. rewrite <- VIEQ. apply (@M_ZF (fun _ => ∅) ax_ext). cbn; tauto. Qed.
imports: Undecidability.FOL(Syntax.Facts Semantics.Tarski.FullFacts) Undecidability.FOL(Sets.ZF) Undecidability.FOL(ZF) Undecidability.FOL.TRAKHTENBROT(hfs) Undecidability.Shared.Libs.DLW.Utils(finite) Undecidability(Shared.ListAutomation) Lia