Definition CReal_opp (x : CReal) : CReal :=
{|
seq := CReal_opp_seq x;
scale := CReal_opp_scale x;
cauchy := CReal_opp_cauchy x;
bound := CReal_opp_bound x
|}.
Notation "- x" := (CReal_opp x) : CReal_scope.
Definition CReal_minus (x y : CReal) : CReal
:= CReal_plus x (CReal_opp y).
Infix "-" := CReal_minus : CReal_scope.

Lemma CReal_plus_opp_l : forall x : CReal,
- x + x == 0.