#[global]
Instance CR_of_Q_morph_T
  : forall {R : ConstructiveReals}, CMorphisms.Proper
      (CMorphisms.respectful Qeq (CReq R)) (CR_of_Q R).

Lemma CRmult_le_0_compat : forall {R : ConstructiveReals} (a b : CRcarrier R), 0 <= a -> 0 <= b -> 0 <= a * b.