#[global]
Instance seq_cv_morph
  : forall (un : nat -> CReal), CMorphisms.Proper
      (CMorphisms.respectful CRealEq CRelationClasses.iffT) (seq_cv un).(* Sharpen the archimedean property : constructive versions of
   the usual floor and ceiling functions. *)
Definition Rfloor (a : CReal)
  : { p : Z  &  inject_Q (p#1) < a < inject_Q (p#1) + 2 }.

Lemma Qpower_2powneg_le_inv: forall (n : positive), (2 * 2 ^ Z.neg n <= 1 # n)%Q.