fact: Definition mb_is_fun (l s : X) := forall p q x x' y, x ∈ l -> x' ∈ l -> p ∈ s -> q ∈ s -> p ≋ ⦅x,y⦆ -> q ≋ ⦅x',y⦆ -> x ≈ x'.
imports: List Arith Nat Lia Max Wellfounded Coq.Setoids.Setoid Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list finite) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.FOL.TRAKHTENBROT(notations fol_ops fo_sig fo_terms fo_logic)