On potential kernels associated with random dynamical systems

Let $(\Theta;, \phi)$ be a continuous random dynamical system defined on a probability space $(\Omega, F, P)$ and taking values on a locally compact Hausdorff space E. The associated potential kernel V is given by $V f(\omega, x) = \int_0^\infty f (\Theta_t \omega, \phi(t, \omega)x)dt, \omega \in \Omega, x \in E$. In this paper, we prove the equivalence of the following statements: 1. The potential kernel of $(\Theta, \phi)$ is proper, i.e. $V f$ is x-continuous for each bounded, x-continuous function with uniformly random compact support. 2. $(\Theta, \phi)$ has a global Lyapunov function, i.e. a function $ L : \Omega \times E \rightarrow (0, \infty) $ which is x-continuous and $ L(\Theta_t\omega, \phi(t,\omega)x) \downarrow 0$ as $ t \uparrow \infty $. In particular, we provide a constructive method for global Lyapunov functions for gradient-like random dynamical systems. This result generalizes an analogous theorem known for deterministic dynamical systems.