fact: Definition fot_definable (f : (nat -> X) -> X) := { t | incl (fo_term_syms t) ls /\ forall φ, fo_term_sem M φ t = f φ }.
imports: List Arith Lia Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list finite) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.FOL.TRAKHTENBROT(notations utils fol_ops fo_sig fo_terms fo_logic)