(* begin hide *)
Notation RmaxLess2 := Rmax_r (only parsing).
(* end hide *)

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(** *        Rabsolu           *)
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Lemma Rcase_abs : forall r, {r < 0} + {r >= 0}.
Definition Rabs r : R :=
match Rcase_abs r with
| left _ => - r
| right _ => r
end.