On a class of stochastic semilinear PDE's

We consider stochastic semilinear partial differential equations with Lipschitz nonlinear terms. We prove existence and uniqueness of an invariant measure and the existence of a solution for the corresponding Kolmogorov equation in the space $L^2(H;\nu )$, where $\nu$ is the invariant measure. We also prove the closability of the derivative operator and an integration by parts formula. Finally, under boundness conditions on the nonlinear term, we prove a Poincar'e inequality, a logarithmic Sobolev inequality and the ipercontractivity of the transition semigroup.