#[global]
Instance CR_cv_morph
: forall {R : ConstructiveReals} (un : nat -> CRcarrier R), CMorphisms.Proper
(CMorphisms.respectful (CReq R) CRelationClasses.iffT) (CR_cv R un).

Lemma CR_cv_minus :
forall {R : ConstructiveReals}
(An Bn:nat -> CRcarrier R) (l1 l2:CRcarrier R),
CR_cv R An l1 -> CR_cv R Bn l2
-> CR_cv R (fun i:nat => An i - Bn i) (l1 - l2).