L. Chayes and K. Shtengel
Lebowitz Inequalities for Ashkin--Teller Systems
(44K, AMS-TeX)

ABSTRACT.  We consider the Ashkin--Teller model with negative four-spin coupling 
but still in the region where the ground state is ferromagnetic. We 
establish the standard Lebowitz inequality as well as the extension 
that is necessary to prove a divergent susceptibility.