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It is widely agreed on that (deductive) database systems for knowledge based applications should support complex data structures. From a database point of view this usually means to provide a collection of constructors that allow to build complex objects out of simpler objects, perhaps combined with some inheritance mechanisms. This way of thinking is determined by such applications as CAD or Multi...
This paper aims at integrating techniques of non-monotonic reasoning about updates and of object-oriented specification of information systems. We present how to utilize defaults in specifications of dynamic system behaviour. Thus overridable rules may be used in specifications which deal not only with state structures, but also with state transitions and sequences. Systems are viewed as societies...
Terminological logics have become a well understood formal basis for taxonomic knowledge representation, both for the semantics (classically by Tarski models) and for the inference services (like concept subsumption, instantiation, classification, and realization) of terminological systems of the KL-ONE family. It has been demonstrated that terminological reasoning can be realized by efficient and...
There is a manifold of meanings we could associate with the term “evolution” in the database arena. This paper tries to categorize some of these into a unique framework, showing similarities and differences. Among the topics touched upon are: extending traditional data models to become “object-oriented”, migrating existing data to (not necessarily OO) databases, schema extension and modification in...
DATALOG¬ is a well-known logical query language, whose expressive power and data complexity under the stable model semantics has been recently determined. In this paper we consider the extension of DATALOG¬ to disjunctive DATALOG¬ (DDL¬), which allows disjunction in the head of program clauses, under the stable model semantics. We investigate and determine the expressiveness and the data complexity...
For natural language understanding and generation, plan generation and recognition, and knowledge representation, it is necessary to represent qualitiave temporal information and to reason with it. Allen's interval calculus provides an appropriate framework for such a task. We introduce a new subclass of Allen's interval algebra we call “ORD-Horn subclass,” which is a strict superset of the “pointisable...
After two decades of experience with relational databases and almost one decade with deductive databases a substantial amount of knowledge for efficient query processing methods and query optimizer technology is broadly available. So far, however, these research and development efforts have not paid too much attention to optimizations based on semantic or heuristic information as it is often demanded...
Building in special theories into first order calculi is used in various applications of deduction to increase efficiency of proof procedures. We give a brief review of methods for the combination of theories with deduction or logic programming. We show how a whole family of first order calculi can be extended for theory handling; these calculi are related to each other by a simulability relation...
Conceptual modelling of complex information systems requires the use of a formal design approach covering both static and dynamic aspects of the system and the modelled Universe of Discourse. Viewing an information system as a collection of communicating objects is close to the intuitive perception of such systems on a conceptual level. Objects have a local state, show a specific behaviour, communicate...
Large amounts of knowledge are available in many knowledge bases for a variety of applications. This knowledge is however usually application specific, and thus not reusable. This paper discusses the problem of making knowledge shareable over applications and reusing it. Three principles are formulated that can form a basis for a methodology for designing sharable knowledge bases. The separation of...
Evolution is a fact of life in information systems. Not only systems evolve but also their development processes. IS environments must therefore be designed for accommodating and managing change. The management of process meta models in repositories is one important step; we show how process traceability models and process guidance models can be developed and related in a standard repository framework...
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