Section Rosser's_Incompleteness.
Definition codeFormula := codeFormula LNT codeLNTFunction codeLNTRelation.
Variable T : System.
Definition T' : fol.System LNN :=
Union _ NN
(fun x : fol.Formula LNN => mem _ T (LNN2LNT_formula x)).

Lemma extendsNN : Included _ NN T'.