We introduce unfounded sets and well-founded partial models, and define the well-founded semantics of a program to be its well-founded partial model. If the well-founded partial model is in fact a total model, we call it the well-founded model. We show that the class of programs possessing a total well-founded model properly includes previously studied classes of 'stratified' and 'locally stratified' programs. We also compare our method with other proposals in the literature, including Clark's 'program completion, ' Fitting's and Kunen's 3-valued interpretations of it, and the 'stable models' of Gelfond and Lifschitz."

This book constitutes the refereed proceedings of the 6th International Conference on Logic Programming and Nonmonotonic Reasoning, LPNMR 2001, held in Vienna, Austria in September 2001. The 22 revised full papers and eleven system descriptions presented with five invited papers were carefully reviewed and rigorously selected. Among the topics addressed are computational logic, declarative information extraction, model checking, inductive logic programming, default theories, stable logic programming, program semantics, incomplete information processing, concept learning, declarative specification, Prolog programming, many-valued logics, etc.

This book constitutes the refereed proceedings of the 5th International Conference on Logic Programming and Nonmonotonic Reasoning, LPNMR '99, held in El Paso, Texas, USA, in December 1999. The volume presents 26 contributed papers and four invited talks, three appearing as extended abstracts and one as a full paper. Topics covered include logic programming, non-monotonic reasoning, knowledge representation, semantics, complexity, expressive power, and implementation and applicatons.

The emergence of new paradigms for data management raises a variety of exciting challenges. An important goal of database theory is to answer these challenges by providing sound foundations for the development of the field. This volume contains the papers selected for the third International Conference on Database Theory, ICDT'90. The conferences in this series are held biannually in beautiful European cities, Rome in 1986 and Bruges in 1988 with proceedings published as volumes 234 and 326 in the same series. ICDT'90 was organized in Paris by the Institut National de Recherche en Informatique et Automatique. The conference features 2 invited presentations and 31 papers selected from 129 submissions. The papers describe original ideas and new results on the foundations of databases, knowledge bases, object-oriented databases, relational theory, transaction management, data structures and deductive databases. The volume offers a good overview of the state of the art and the current trends in database theory. It should be a valuable source of information for researchers interested in the field.

Baral shows how to write programs that behave intelligently, by giving them the ability to express knowledge and to reason. This book will appeal to practising and would-be knowledge engineers wishing to learn more about the subject in courses or through self-teaching.

This is the second in a series of workshops that are bringing together researchers from the theoretical end of both the logic programming and artificial intelligence communities to discuss their mutual interests. This workshop emphasizes the relationship between logic programming and non-monotonic reasoning.Luis' Moniz Pereira is Professor in the Department of Computer Science at the Universidade Nova Lisboa, Portugal. Anil Nerode is Professor and Director of the Mathematical Sciences Institute at Cornell University.Topics include: Stable Semantics. Autoepistemic Logic. Abduction. Implementation Issues. Well-founded Semantics. Truth Maintenance. Probabilistic Theories. Applications. Default Logic. Diagnosis. Complexity and Theory. Handling Inconsistency.