Definition Z_to_group_nat_fun : ZZ -> G.

Lemma Zl4 : forall p p0 : positive, Equal (Z_to_group_nat_fun (Zpos p + Zneg p0)%Z) (sgroup_law G (nat_to_group (nat_of_P p)) (group_inverse G (nat_to_group (nat_of_P p0)))).