Deterministic approximation for the cover time of trees

We present a deterministic algorithm that given a tree T with n vertices, a starting vertex v and a slackness parameter ǫ > 0, estimates within an additive error of ǫ the cover and return time, namely, the expected time it takes a simple random walk that starts at v to visit all vertices of T and return to v. The running time of our algorithm is polynomial in n/ǫ, and hence remains polynomial in n also for ǫ = 1/n. We also show how the algorithm can be extended to estimate the expected cover (without return) time on trees.