Ontology was once understood to be the philosophical inquiry into the structure of reality: the analysis and categorization of what there is. Recently, however, a field called ontology has become part of the rapidly growing research industry in information technology. The two fields have more in common than just their name.

Theory and Applications of Ontology is a two-volume anthology that aims to further an informed discussion about the relationship between ontology in philosophy and ontology in information technology. It fills an important lacuna in cutting-edge research on ontology in both fields, supplying stage-setting overview articles on history and method, presenting directions of current research in either field, and highlighting areas of productive interdisciplinary contact.

Theory and Applications of Ontology: Computer Applications presents ontology in ways that philosophers are not likely to find elsewhere. The volume offers an overview of current research in ontology, distinguishing basic conceptual issues, domain applications, general frameworks, and mathematical formalisms. It introduces the reader to current research on frameworks and applications in information technology in ways that are sure to invite reflection and constructive responses from ontologists in philosophy.

Roberto Poli (B.A. in sociology, with honors, Ph.D. on ontology for knowledge engineers, Utrecht) is editor-in-chief of Axiomathes (Springer), a peer-reviewed academic journal devoted to the study of ontology and cognitive systems, editor of Categories (Ontos), and member of the Academic Board of Directors of the Metanexus Institute, Philadelphia. His research interests include (1) ontology, in both its traditional philosophical understanding and the new, computer-oriented, understanding, (2) the theory of values and the concept of person and (3) anticipatory systems, i.e. system able to take decisions according to their possible future development. Poli has published four books, edited or co-edited more than 20 books or journals special issues and published more than 150 scientific papers. He teaches Applied Ethics and Futures Studies at the Faculty of Sociology and gives a course in Ontology at the Faculty of Literature and Philosophy, University of Trento.

Michael J. Healy received a B.A degree in mathematics from Eastern Washington University at Cheney, Washington in 1965 and a M.S. in mathematics from the University of Idaho in 1967. From 1967 through 2001 he worked for The Boeing Company, first as a consultant in nonlinear programming and, beginning in 1989, in research. His research spanned neural networks, machine learning, formal verification, and applications of category theory in software synthesis, knowledge based systems (KBS) engineering (KBSE), and knowledge representation and ontologies for KBS interoperability. He is now a Senior Research Scholar in the Electrical and Computer Engineering Department (ECE) at the University of New Mexico, which he joined in 2000. He continues to pursue his research interests in the semantics of neural networks, cognitive neuroscience, knowledge representation, and ontologies for systems, including computational, cognitive, and social systems. Category theory is the centralma thematical discipline for his research, with a particular focus upon categorical logic and model theory.

Achilles D. Kameas received his Engineering Diploma (in 1989) and his Ph.D. (in 1995, in Human-Computer Interaction), both from the Department of Computer Engineering and Informatics, Univ. of Patras, Greece. Since 2003, he is an Assistant Professor with the Hellenic Open University, where he teaches software design and engineering. He is also the Director of Research Unit 3 / DAISy (Designing Ambient Intelligent Systems) (http://daisy.cti.gr) at the Research Academic Computer Technology Institute (CTI). Since 2007 he is Deputy Dean of the School of Sciences and Technology (SST) of the Hellenic Open University and Director of the e-Comet Lab (Educational Content, Methodologies and Technologies Lab) (http://eeyem.eap.gr). He has participated as researcher, engineer, group leader or scientific coordinator in several EU R&D projects, such as e-Gadgets, Plants, Social, Astra and Atraco. He has published over 100 journal articles, conference papers and book chapters, authored three university textbooks and co-edited more than five books.He is a member of the Advisory Board of Panorama CA and the scientific committee of the Intelligent Environments conferences; in the past he was elected in the steering boards of the Disappearing Computer network and Convivio network. His current research interests include architectures, languages and tools for ubiquitous computing systems, engineering of ubiquitous computing applications, and engineering and application of ontologies and ontology matching. He is a voting member of IEEE, IEEE CS, ACM and ACM SIGCHI. He is a member of Technical Chamber of Greece, Hellenic AI Society and Hellenic Society for the application of ICT in Education.

The Interplay Between Ontology as Categorial Analysis and Ontology as Technology.- Ontological Architectures.- Organization and Management of Large Categorical Systems.- The Information Flow Approach to Ontology-Based Semantic Alignment.- Ontological Evaluation and Validation.- Tools for Ontology Engineering and Management.- Ontological Tools: Requirements, Design Issues and Perspectives.- Using the Unified Foundational Ontology (UFO) as a Foundation for General Conceptual Modeling Languages.- Lightweight Ontologies.- WordNet.- Controlled English to Logic Translation.- Cyc.- Ontological Foundations of dolce.- General Formal Ontology (GFO): A Foundational Ontology for Conceptual Modelling.- Ontologies in Biology.- The Ontology of Medical Terminological Systems: Towards the Next Generation of Medical Ontologies.- Ontologies of Language and Language Processing.- Business Ontologies.- Ontologies for E-government.- An Ontology-Driven Approach and a Context Management Framework for Ubiquitous Computing Applications.- Category Theory as a Mathematics for Formalizing Ontologies.- Issues of Logic, Algebra and Topology in Ontology.- The Institutional Approach.- Ontology Engineering, Universal Algebra, and Category Theory.