proposition: Lemma labelling_S: forall f n, labelling (Datatypes.S n) f == labelling n f + xif (f n) (RegExp.var (num_of_nat n): regex) 0.
proof: Proof. intros. apply sum_enter_right. Qed.
imports: ATBR(Common) ATBR(Classes) ATBR(Graph) ATBR(Monoid) ATBR(SemiLattice) ATBR(SemiRing) ATBR(KleeneAlgebra) ATBR(MxGraph) ATBR(MxSemiLattice) ATBR(MxSemiRing) ATBR(MxKleeneAlgebra) ATBR(DKA_Definitions) ATBR(DKA_CheckLabels) ATBR(StrictStarForm) ATBR(Utils_WF) Coq(Relations)