Definition Q_eq_dec : forall x y : Q, {x = y} + {x <> y}.

Theorem Qpositive_le_sub_simpl_r : forall x y z : Qpositive, Qpositive_le z x -> Qpositive_le z y -> z <> x -> z <> y -> Qpositive_le (Qpositive_sub x z) (Qpositive_sub y z) -> Qpositive_le x y.