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

Lemma CRmult_pos_pos : forall {R : ConstructiveReals} (x y : CRcarrier R), 0 < x * y -> 0 <= x -> 0 <= y -> 0 < x.