The Web has become the world's largest database, with search being the main tool that allows organizations and individuals to exploit its huge amount of information. Search on the Web has been traditionally based on textual and structural similarities, ignoring to a large degree the semantic dimension, i.e., understanding the meaning of the query and of the document content. Combining search and semantics gives birth to the idea of semantic search. Traditional search engines have already advertised some semantic dimensions. Some of them, for instance, can enhance their generated result sets with documents that are semantically related to the query terms even though they may not include these terms. Nevertheless, the exploitation of the semantic search has not yet reached its full potential.

In this book, Roberto De Virgilio, Francesco Guerra and Yannis Velegrakis present an extensive overview of the work done in Semantic Search and other related areas. They explore different technologies and solutions in depth, making their collection a valuable and stimulating reading for both academic and industrial researchers. The book is divided into three parts. The first introduces the readers to the basic notions of the Web of Data. It describes the different kinds of data that exist, their topology, and their storing and indexing techniques. The second part is dedicated to Web Search. It presents different types of search, like the exploratory or the path-oriented, alongside methods for their efficient and effective implementation. Other related topics included in this part are the use of uncertainty in query answering, the exploitation of ontologies, and the use of semantics in mashup design and operation. The focus of the third part is on linked data, and more specifically, on applying ideas originating in recommender systems on linked data management, and on techniques for the efficiently querying answering on linked data.

Autorentext

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.

Inhalt
Introduction.- Part I Introduction toWeb of Data.- Topology of the Web of Data.- Storing and Indexing Massive RDF Data Sets.- Designing Exploratory Search Applications upon Web Data Sources.- Part II Search over the Web.- Path-oriented Keyword Search query over RDF.- Interactive Query Construction for Keyword Search on the SemanticWeb.- Understanding the Semantics of Keyword Queries on Relational DataWithout Accessing the Instance.- Keyword-Based Search over Semantic Data.- Semantic Link Discovery over Relational Data.- Embracing Uncertainty in Entity Linking.- The Return of the Entity-Relationship Model: Ontological Query Answering.- Linked Data Services and Semantics-enabled Mashup.- Part III Linked Data Search engines.- A Recommender System for Linked Data.- Flint: from Web Pages to Probabilistic Semantic Data.- Searching and Browsing Linked Data with SWSE.