(** * Rdiv *)
(** Rewritings *)

(* Specifications: *)
Lemma Rdiv_1 : forall x : R, x / 1 = x.
Lemma Rdiv_plus : forall a b c d : R, b <> 0 -> d <> 0 ->
a / b + c / d = (a * d + c * b) / (b * d).
Lemma Rdiv_minus : forall a b c d : R, b <> 0 -> d <> 0 ->
a / b - c / d = (a * d - c * b) / (b * d).