Definition Ratio x y : {ratio R} := insubd ratio0 (x, y).

(* Specifications: *)
Lemma numer_Ratio x y : y != 0 -> (Ratio x y).1 = x.
Lemma Ratio0 x : Ratio x 0 = ratio0.
Canonical equivf_equiv := EquivRel equivf equivf_refl equivf_sym equivf_trans.