proposition: Lemma Zgcd_coeff_b_abs : forall a b : Z, Zgcd_coeff_b a b = (Z.sgn b * Zgcd_coeff_b (Z.abs a) (Z.abs b))%Z.
proof: Proof. intros. unfold Zgcd_coeff_b in |- *. rewrite Zgcd_duv_abs. elim (Zgcd_duv (Z.abs a) (Z.abs b)); intros d uv; elim uv; intros u v. reflexivity. Qed.
imports: CoRN.model.Zmod.ZDivides Coq.Init.Wf Coq(Lia)