proposition: Fact fo_term_sem_fix_0 φ n : ⟦in_var n⟧ φ = φ n.
proof: Proof. trivial. Qed.
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)