Consider an infinite dimensional diffusion process process on , where is the circle, defined by the action of its generator on local functions as . Assume that the coefficients, and are smooth, bounded, finite range with uniformly bounded second order partial derivatives, that is only a function of and that . Suppose is an invariant product measure. Then, if is the Lebesgue measure or if , it is the unique invariant measure. Furthermore, if is translation invariant, then...