proposition: Fact fot_word_eq w i : fot_word (fot_word_var w i) = w.
proof: Proof. induction w; simpl; f_equal; auto. Qed.
imports: List Arith Bool 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 fol_ops fo_sig fo_terms fo_logic fo_sat Sig_no_syms)