fact: Fixpoint fo_term_subst σ t := match t with | in_var x => σ x | in_fot v => in_fot (vec_map (fo_term_subst σ) 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)