Roberto De Virgilio is currently working at the Università Roma Tre as a research/postdoctoral fellow. His research interests are data integration, Web-based information systems, XML data management, Semantic Web, data modelling and database design, and model management.  He is the author of several papers on Web information systems management and Semantic Web technologies and organizer of several international events to promote research on Semantic Web Data Management field. Francesco Guerra is a faculty member at the University of Modena and Reggio Emilia where he received his Ph.D. in Information Engineering in 2004. His main research interests include the integration of heterogeneous information sources, Semantic Web and keyword-based searches. He has participated in several Italian and European projects and he was a reviewer for international conferences and journals. Yannis Velegrakis is a faculty member at the University of Trento, with expertise in Schema Mapping, Interoperability, Heterogeneous Information Integration, Semantic Web, View Management, Social Networking and Keyword searching. Prior to joining the University of Trento, he held a researcher position at ATT Research Labs (USA) and had also spent time as a visitor at the IBM Almaden Research Center, the Center of Advanced Studies of the IBM Toronto Lab, and the University of California, Santa-Cruz. He is a member of the editorial board of the Journal on Data Semantics, and a reviewer for many international conferences and journals.