Terminological Knowledge Representation Systems (TKRSs) are tools for designing and using knowledge bases that make use of terminological languages (or concept languages). The TKRS we consider in this paper is of practical interest since it goes beyond the capabilities of presently available TKRSs. First, our TKRS is equipped with a highly expressive concept, language, called ALCNR, including general complements of concepts, number restrictions and role conjunction. Second, it allows one to express inclusion statements between general concepts, in particular to express terminological cycles. We provide a sound, complete and terminating calculus for reasoning in ALCNR-knowledge bases based on the general technique of constraint systems.

One of the main characteristics of knowledge representation systems based on the description of concepts is the clear distinction between terminological and assertional knowledge. Although this characteristic leads to several computational and representational advantages, it usually limits the expressive power of the system. For this reason, some attempts have been done, allowing for a limited form of amalgamation between the two components and a more complex interaction between them. In particular, one of these attempts is based on letting the individuals to be referenced in the concept expressions. This is generally performed by admitting a constructor for building a concept from a set of enumerated individuals. In this paper we investigate on the consequences of introducing constructors of this type in the concept description language. We also provide a complete reasoning procedure to deal with these constructors and we obtain some complexity results on it. 1 Introduction The ide...

This paper presents an analysis of purpose clauses in the context of instruction understanding. Such analysis shows that goals affect the interpretation and / or execution of actions, lends support to the proposal of using generation and enablement to model relations between actions, and sheds light on some inference processes necessary to interpret purpose clauses.

In this paper, we construct a new concept description language intended for representing dynamic and intensional knowledge. The most important feature distinguishing this language from its predecessors in the literature is that it allows applications of modal operators to all kinds of syntactic terms: concepts, roles and formulas. Moreover, the language may contain both local (i.e., state-dependent) and global (i.e., state-independent) concepts, roles and objects. All this provides us with the most complete and natural means for re ecting the dynamic and intensional behaviour of application domains. We construct a satis ability checking (mosaic-type) algorithm for this language (based on ALC) in(i) arbitrary multimodal frames, (ii) frames with universal accessibility relations (for knowledge) and (iii) frames with transitive, symmetrical and euclidean relations (for beliefs). On the other hand, it is shown that the satisfaction problem becomes undecidable if the underlying frames are arbitrary strict linear orders, hN; <i, or the language contains the common knowledge operator for n 2 agents. 1

Reasoning with terminological logics is a subfield in the area of knowledge representation that evolved from the representation language kl-one. Its main purpose is to automatically determine the location of a a new concept description (or object description) in a partially ordered set of given concepts. It seems to be a promising approach to apply the techniques developed in this area to the development of new object-based database models. The main advantages are a uniform query and database definition language and the utilization of an indexing technique, which we call semantic indexing.

Representing and reasoning with both temporal constraints between classes of events (e.g., between the types of actions needed to achieve a goal) and temporal constraints between instances of events (e.g., between the specific actions being executed) is a ubiquitous task in many areas of computer science, such as planning, workflow, guidelines and protocol management. The temporal constraints between the classes of events must be inherited by the instances, and the consistency of both types of constraints must be checked. In this paper, we propose a general-purpose domain-independent knowledge server dealing with these issues. In particular, we propose a formalism to represent temporal constraints, we show two algorithms to deal with inheritance and to perform temporal consistency checking, and we study the properties of the algorithms.

This paper describes the DD framework for domain modelling in information systems engineering. Such...

Terminological representation systems permit the construction of knowledge bases and schemata around the notion of concepts, roles, and instantiating objects. Inferential services they provide include checking for inconsistencies in and classification of concept and object descriptions. To improve their performance, several systems store derived propositions together with user-told data in the knowledge base. In this report we address the problem of retraction of object descriptions for systems that employ such a generative implementation. We adopt a data dependency network approach. Contents 1 Introduction 1 2 Retraction in Terminological Representation Systems 2 3 Processing Retractions of Object Descriptions 6 3.1 Minimal and Maximal Approaches : : : : : : : : : : : : : : : : 6 3.2 A Naive Approach : : : : : : : : : : : : : : : : : : : : : : : : : 7 3.3 A Semi-Naive Approach Based on Object Dependencies : : : : : 8 3.4 Labeled Dependency Links : : : : : : : : : : : : : : : : : :...

Today, terminological knowledge representation systems have reached a level of maturity which makes their use for real world applications feasible. However, the construction of practical knowledge representation management systems (KBMS) requires more than a well-de ned representation formalism and reasoning algorithm. Flexibility and system integration are two important issues for any KBMS. In this paper, we propose an extension of the back terminological representation system which allows the integration of externally realized procedures into the representation formalism. For that purpose, we introduce a new language construct External Function which serves as an interface to arbitrary host-language procedures. External Functions allow ustointegrate forms of domain speci c knowledge such as arithmetic computations into back which can not be expressed e ciently in terminological representation systems. We show how results of computations can be integrated into the reasoning process and how Computed

Both object-oriented database systems and knowledge representation systems based on description logics address the need for dealing with complex, highly structured data in a simple, e cient, and exible