fact: Fixpoint fo_term_size t : nat := match t with | in_var x => 1 | in_fot v => 1 + lsum (vec_list (vec_map fo_term_size v)) end.
imports: List Arith Lia Eqdep_dec Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list utils_nat finite) Undecidability.Shared.Libs.DLW.Vec(pos vec) Undecidability.FOL.TRAKHTENBROT(notations utils decidable fol_ops fo_sig)