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This introduction presents the main motivations for the development of Description Logics (DL) as a formalism for representing knowledge, as well as some important basic notions underlying all systems that have been created in the DL tradition. In addition, we provide the reader with an overview of the entire book and some guidelines for reading it. We(More)
We present an integrated system for knowledge representation, calledAL -log, based on description logics and the deductive database language Datalog. AL-log embodies two subsystems, called structural and relational. The former allows for the definition of structural knowledge about classes of interest (concepts) and membership relation between objects and(More)
tively used in the construction of knowledge-based applications in several domains (see for example Wright et al. 1993), like connguration and software engineering. Recently we have seen attempts to use them in the elds of machine learning (see for example Cohen and Hirsh 1994) and planning (see for example Devambu and Litman 1991, Weida and Litman 1992,(More)
ur K ¨ unstliche In-telligenz, DFKI) with sites in Kaiserslautern and Saarbrücken is a non-profit organization which was founded in 1988. The DFKI conducts application-oriented basic research in the field of artificial intelligence and other related subfields of computer science. The overall goal is to construct systems with technical knowledge and common(More)
Description iogics (aiso caiied terminoiogicai iogics, or concept ianguagesj are fragments of first-order logic that provide a formal account of the basic features of frame-based systems. However, there are aspects of frame-based systems-such as nonmonotonic reasoning and procedural rules-that cannot be characterized in a standard first-order framework.(More)
Information Integration is one of the core problems in distributed databases, cooperative information systems, and data warehousing, which are key areas in the software development industry. Two critical factors for the design and maintenance of applications requiring Information Integration are conceptual modeling of the domain, and reasoning support over(More)
The notion of class is ubiquitous in computer science and is central in many formalisms for the representation of structured knowledge used both in knowledge representation and in databases. In this paper we study the basic issues underlying such representation formalisms and single out both their common characteristics and their distinguishing features.(More)
This introduction presents the main motivations for the development of Description Logics (DL) as a formalism for representing knowledge, as well as some important basic notions underlying all systems that have been created in the DL tradition. In addition, we provide the reader with an overview of the entire book and some guidelines for reading it. We(More)
It is a common opinion that subsumption is the central reasoning task in frame-based knowledge representation languages (or concept languages). Intuitively, a concept C subsumes another concept D if the set of objects represented by C is a superset of the one represented by D. When individual objects are taken into account, the basic deduc-tive task for(More)