Notation Zgcd_Zabs := Z.gcd_abs_l (only parsing).Notation Zgcd_0 := Z.gcd_0_r (only parsing).Notation Zgcd_1 := Z.gcd_1_r (only parsing).

(* Specifications: *)
Theorem Zgcd_1_rel_prime : forall a b, Z.gcd a b = 1 <-> rel_prime a b.