Functional Scheme Z_to_Q_ind := Induction for Z_to_Q Sort Prop.

Lemma Z_to_Qmult_POS_NEG :
forall p1 p2 : positive,
Z_to_Q (Zpos p1 * Zneg p2) = Qmult (Z_to_Q (Zpos p1)) (Z_to_Q (Zneg p2)).