proposition: Lemma gcd_unq : forall (d1 d2 : nat) (x y : Z), gcd x y d1 -> gcd x y d2 -> d1 = d2.
proof: Proof. unfold gcd in |- *. intros. elim H. elim H0. intros. apply le_antisym. apply H2. assumption. apply H4. assumption. Qed.
imports: ZArith Wf_nat lemmas natZ divides modulo