The Semantic Web: Research and Applications : 8th Extended Semantic Web Conference, ESWC 2011, Heraklion, Crete, Greece, May 29 . June 2, 2011. Proceedings, Part I - Grigoris Antoniou, Marko Grobelnik, Elena Simperl, Bijan Parsia, Dimitris Plexousakis, Pieter Leenheer, Jeff Pan ((Lecture Notes in Computer Science))