Induced measures of simple random walks on Sierpinski graphs

Abstract

In \cite{[K]}, Kaimanovich defined an augmented rooted tree $(X,E)$ corresponding to the Sierpinski gasket $K$, and showed that the Martin boundary of the simple random walk $\{Z_n\}$ on it is homeomorphic to $K$. It is of interest to determine the hitting distributions $v_{\mathbf{x}}(\cdot )={\mathbb{P}}_{\mathbf{x}}\{{\lim }_{n\to \infty }{Z}_n\in \cdot \}$ induced on $K$. Using a reflection principle based on the symmetries of $K$, we show that if the walk starts at the root of $(X,E)$, the hitting distribution is exactly the normalized Hausdorff measure $\mu$ on $K$. In particular, each $v_{\mathbf{x}}$, $\mathbf{x}\in X$, is absolutely continuous with respect to $\mu$. This answers a question of Kaimanovich [K, Problem 4.14]. The argument can be generalized to other symmetric self-similar sets.

arXiv comment19 pages, 10 figures