Omer Reingold, Luca Trevisan, Salil P. Vadhan. Pseudorandom walks on regular digraphs and the RL vs. L problem. In Jon M. Kleinberg, editor, Proceedings of the 38th Annual ACM Symposium on Theory of Computing, Seattle, WA, USA, May 21-23, 2006. pages 457-466, ACM, 2006. [doi]
Abstract is missing.