  Following the idea, recently, proposed by the present authors for the
two-level pairing model, the Lipkin model is reexamined. It is a natural
generalization of the method already developed by the present authors with
Kuriyama. This model is a schematic model for many-fermion system and obeys the
su(2)-algebra. It is shown that the use of the Schwinger boson representation,
the model is expressed in terms of the su(1,1) times su(1,1)-algebra and with
the aid of the MYT mapping method, it is disguised from the orginal form in
terms of the Holstein-Primakoff representation. Further, under various coherent
states, the classical counterparts are derived. It is concluded that the Lipkin
model can be treated in the common ring as that of the two-level pairing model.
