proposition: Lemma numeral_lt k l : k < l -> numeral k ∈ numeral l.
proof: Proof. Proof using VIEQ M_ZF. induction 1; cbn; apply sigma_el; auto. Qed.
imports: Undecidability.FOL(Syntax.Facts Semantics.Tarski.FullFacts ZF) Undecidability.FOL.Sets(ZF binZF) Undecidability.FOL.Sets.Models(Aczel Aczel_CE Aczel_TD) Coq(Lia)