proposition: Lemma M_pair x y z : x ∈ {y; z} <-> x = y \/ x = z.
proof: Proof. Proof using M_FST VIEQ. rewrite M_adj. rewrite M_adj. intuition. now apply M_eset in H. Qed.
imports: Undecidability.FOL(Syntax.Facts Semantics.Tarski.FullFacts FST) Undecidability.FOL(Sets.FST) Undecidability.FOL.TRAKHTENBROT(hfs) Undecidability.Shared.Libs.DLW.Utils(finite) Undecidability(Shared.ListAutomation) Coq(Lia)