Continuous Symmetry and Other Methods

Abstract

In this chapter we have joined, §§1–3, a study of the case where the fiber Φ is equipped with a continuous symmetry — typically, Φ , is a circle or a sphere —, to a brief discussion of two other approaches among the many that have been created to treat the problem of phase transition, especially upon a lattice. The methods to be presented here, that of Onsager, §4, and the combinatorial method, §5, have played important roles in the historical developement of the discipline and remain useful