Random Walks, Boundaries and Spectra : [contains the joint proceedings of the workshop on Boundaries that took place in Graz, from June 29–July 3, and the Alp-Workshop that was held immediately afterwards in Sankt Kathrein am Offenegg, on the weekend July 4–5, 2009]/ edited by Daniel Lenz, Florian Sobieczky, Wolfgang Woess (2011)