Ontology-Based Query Processing for Global Information Systems : Springer : 9780792373759 : 0792373758 : 31 Jul 2001 : This work is a revision of the doctoral dissertation of Eduardo Mena pre­ sented to the Department of Computer Science and System Engineering at the University of Zaragoza (Spain) in November 1998 [Mena 98]. The OBSERVER system was developed as a result of this Ph.D. thesis. This book is composed of eight chapters. In Chapter 1 we introduce our rationale for writing a book about systems that process queries in global information systems. Then in Chapter 2 we review the techno­ logical context for our work, including distributed and heterogeneous environments and the use of ontologies. We also compare related work to our own. Chapter 3 presents our proposed global system architecture for query processing in global information systems. The main modules in the architecture and the main steps given to process a query are briefly introduced. Chapters 4 through 7 provide a d