ON LOW-ENERGY FIELD-THEORIES

A class of generalized Ising models is examined with a view to extract ing a low energy sector comprising Dirac fermions coupled to Yang-Mill s vectors. The main feature of this approach is a set of gap equations , covariant with respect to one of the 4-dimensional crystallographic space groups. The Dirac propagator is determined a la generalized Namb u-Jona Lasinio mechanism as a solution of these gap equations.