Definition CReal_plus (x y : CReal) : CReal :=
{|
  seq := CReal_plus_seq x y;
  scale := CReal_plus_scale x y;
  cauchy := CReal_plus_cauchy x y;
  bound := CReal_plus_bound x y
|}.Infix "+" := CReal_plus : CReal_scope.Definition CReal_opp_seq (x : CReal) :=
  (fun n : Z => - seq x n).Definition CReal_opp_scale (x : CReal) : Z :=
  x.(scale).

Lemma CReal_opp_cauchy : forall (x : CReal), QCauchySeq (CReal_opp_seq x).