Expected hitting time estimates on finite graphs

Abstract

The expected hitting time from vertex $a$ to vertex $b$, $H(a,b)$, is the expected value of the time it takes a random walk starting at $a$ to reach $b$. In this paper, we give estimates for $H(a,b)$ when the distance between $a$ and $b$ is comparable to the diameter of the graph, and the graph satisfies a Harnack condition. We show that, in such cases, $H(a,b)$ can be estimated in terms of the volumes of balls around $b$. Using our results, we estimate $H(a,b)$ on various graphs, such as rectangular tori, some convex traces in ${\mathbb{Z}}^d$, and fractal graphs. Our proofs use heat kernel estimates.

24 pages, 5 figures