H. J. Yoo, H. H. Lee, H. I. Kim, S. G. Jo, S. D. Choi
Equilibrium statistical mechanics for classical and quantum unbounded 
spin systems
(243K, Latex2e, Postcript. )

ABSTRACT.  We study the equilibrium statistical mechanics for classical and quantum 
unbounded spin systems interacting via superstable and regular interactions. 
We show that in classical systems any DLR measure satisfies the Gibbs 
variational equality and the converse is also true if the interaction is of 
finite range. For quantum systems, we show that the (weak) KMS state constructed 
via the thermodynamic limit of finite volume Green's functions satisfies the 
Gibbs variational equality.