(** [divide] is decidable *)

Axiom divide_dec : forall a b : Z, {(a | b)%Z} + {~ (a | b)%Z}.

(* Specifications: *)
Lemma prime_mult : forall p : Z, prime p -> forall a b : Z, (p | a * b)%Z -> (p | a)%Z \/ (p | b)%Z.