proposition: Lemma Metric_d_com : forall X : CPsMetricSpace, com (Metric_d X).
proof: Proof. intro X. unfold com in |- *. intros x y. unfold Metric_d in |- *. simpl in |- *. unfold metric_d in |- *. apply ax_d_com. apply CPsMetricSpace_is_CPsMetricSpace. Qed.
imports: CoRN.metrics.Prod_Sub CoRN.metrics.Equiv