Fernando Bobillo Paulo Cesar G. da Costa Claudia d'Amato Nicola Fanizzi Kathryn B. Laskey Kenneth J. Laskey Thomas Lukasiewicz Trevor P. Martin Matthias Nickles Michael Pool Pavel Smrz Proceedings of the Fourth International Workshop on Uncertainty Reasoning for the Semantic Web, Karlsruhe, Germany, October 26, 2008 URSW CEUR-WS.org CEUR Workshop Proceedings 423 2008 db/conf/semweb/ursw2008.html