Module Zabs2Nat.
(** Results about [Z.abs_nat], converting absolute values of [Z] integers to [nat]. *)
(** [Z.abs_nat], basic equations *)
(** [Z.abs_nat] and usual operations, with non-negative integers *)

Lemma inj_add n m : 0<=n -> 0<=m ->
Z.abs_nat (n+m) = (Z.abs_nat n + Z.abs_nat m)%nat.