Rough Path Theory to approximate Random Dynamical Systems

Abstract

We consider the rough differential equation $dY=f(Y)d\bm \om$ where $\bm \om=(\omega,\bbomega)$ is a rough path defined by a Brownian motion $\omega$ on $\RR^m$. Under the usual regularity assumption on $f$, namely $f\in C^3_b (\RR^d, \RR^{d\times m})$, the rough differential equation has a unique solution that defines a random dynamical system $\phi_0$. On the other hand, we also consider an ordinary random differential equation $dY_\delta=f(Y_\delta)d\omega_\de$, where $\omega_\de$ is a random process with stationary increments and continuously differentiable paths that approximates $\omega$. The latter differential equation generates a random dynamical system $\phi_\delta$ as well. We show the convergence of the random dynamical system $\phi_\delta$ to $\phi_0$ for $\delta\to 0$ in H\"older norm.