fact: Definition up_f `{funcs_signature} (σf : nat -> forall ar, function ar) ar := econs (@var_func _ 0 ar) (fun x ar' => (σf x ar')[shift ar]f).
imports: Arith Lia Vector Undecidability.Shared.Libs.PSL(Vectors) Undecidability.SOL.Util(Syntax) Undecidability.SOL.SOL