Module NAddProp (Import N : NAxiomsMiniSig').
Include NBaseProp N.
(** For theorems about [add] that are both valid for [N] and [Z], see [NZAdd] *)
(** Now comes theorems valid for natural numbers but not for Z *)

Theorem eq_add_1 : forall n m,
n + m == 1 -> n == 1 /\ m == 0 \/ n == 0 /\ m == 1.