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A Scheme for Integrating Concrete Domains into Concept Languages
, 1991
"... A drawback which concept languages based on klone have is that all the terminological knowledge has to be defined on an abstract logical level. In many applications, one would like to be able to refer to concrete domains and predicates on these domains when defining concepts. Examples for such conc ..."
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Cited by 262 (20 self)
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A drawback which concept languages based on klone have is that all the terminological knowledge has to be defined on an abstract logical level. In many applications, one would like to be able to refer to concrete domains and predicates on these domains when defining concepts. Examples for such concrete domains are the integers, the real numbers, or also nonarithmetic domains, and predicates could be equality, inequality, or more complex predicates. In the present paper we shall propose a scheme for integrating such concrete domains into concept languages rather than describing a particular extension by some specific concrete domain. We shall define a terminological and an assertional language, and consider the important inference problems such as subsumption, instantiation, and consistency. The formal semantics as well as the reasoning algorithms are given on the scheme level. In contrast to existing klone based systems, these algorithms will be not only sound but also complete. The...
Decidable reasoning in terminological knowledge representation systems
 Journal of Artificial Intelligence Research
, 1993
"... 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. ..."
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Cited by 185 (12 self)
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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 ALCNRknowledge bases based on the general technique of constraint systems.
Terminological Reasoning is Inherently Intractable
 ARTIFICIAL INTELLIGENCE
, 1990
"... Computational tractability has been a major concern in the area of terminological knowledge representation and reasoning. However, all analyses of the computational complexity of terminological reasoning are based on the hidden assumption that subsumption in terminologies reduces to subsumption of c ..."
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Cited by 147 (11 self)
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Computational tractability has been a major concern in the area of terminological knowledge representation and reasoning. However, all analyses of the computational complexity of terminological reasoning are based on the hidden assumption that subsumption in terminologies reduces to subsumption of concept descriptions without a significant increase in computational complexity. In this paper it will be shown that this assumption, which seems to work in the "normal case," is nevertheless wrong. Subsumption in terminologies turns out to be coNPcomplete for a minimal terminological representation language that is a subset of every useful terminological language.
An Empirical Analysis of Optimization Techniques for Terminological Representation Systems  or: Making KRIS get a move on
, 1992
"... We consider different methods of optimizing the classification process of terminological representation systems, and evaluate their effect on three different types of test data. Though these techniques can probably be found in many existing systems, until now there has been no coherent description o ..."
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Cited by 140 (13 self)
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We consider different methods of optimizing the classification process of terminological representation systems, and evaluate their effect on three different types of test data. Though these techniques can probably be found in many existing systems, until now there has been no coherent description of these techniques and their impact on the performance of a system. One goal of this paper is to make such a description available for future implementors of terminological systems. Building the optimizations that came off best into the kris system greatly enhanced its efficiency.
CARIN: A Representation Language Combining Horn Rules and Description Logics
, 1996
"... . We describe CARIN, a novel family of representation languages, which integrate the expressive power of Horn rules and of description logics. We address the key issue in designing such a language, namely, providing a sound and complete inference procedure. We identify existential entailment as a c ..."
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Cited by 97 (1 self)
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. We describe CARIN, a novel family of representation languages, which integrate the expressive power of Horn rules and of description logics. We address the key issue in designing such a language, namely, providing a sound and complete inference procedure. We identify existential entailment as a core problem in reasoning in CARIN, and describe an existential entailment algorithm for CARIN languages whose description logic component is ALCNR. This algorithm entails several important results for reasoning in CARIN, most notably: (1) a sound and complete inference procedure for non recursive CARINALCNR, and (2) an algorithm for determining rule subsumption over ALCNR. 1 Introduction Horn rule languages have formed the basis for many Artificial Intelligence application languages because their expressive power is sufficient for many applications, and they have good computational properties. One of the significant limitations of Horn rules is that they are not expressive enough to mod...
A Terminological Knowledge Representation System with Complete Inference Algorithms
 In Proceedings of the First International Workshop on Processing Declarative Knowledge
, 1991
"... The knowledge representation system klone rst appeared in 1977. Since then many systems based on the idea of klone have been built. The formal modeltheoretic semantics which has been introduced for klone languages [BL84] provides means for investigating soundness and completeness of inference al ..."
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Cited by 96 (19 self)
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The knowledge representation system klone rst appeared in 1977. Since then many systems based on the idea of klone have been built. The formal modeltheoretic semantics which has been introduced for klone languages [BL84] provides means for investigating soundness and completeness of inference algorithms. It turned out that almost all implemented klone systems such as back, kltwo, loom, nikl, sbone use sound but incomplete algorithms.
The GRAIL concept modelling language for medical terminology
 ARTIFICIAL INTELLIGENCE IN MEDICINE
, 1997
"... ..."
Subsumption Algorithms for Concept Description Languages
 In ECAI90
, 1990
"... We investigate subsumption algorithms for logicbased knowledge representation languages of the klone family. We define an attributive concept description language that contains the logical connectives conjunction, disjunction, and negation, as well as role quantification, number restrictions and r ..."
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Cited by 83 (7 self)
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We investigate subsumption algorithms for logicbased knowledge representation languages of the klone family. We define an attributive concept description language that contains the logical connectives conjunction, disjunction, and negation, as well as role quantification, number restrictions and role intersection. We describe a rule based calculus to decide subsumption in this language, that closely resembles the tableaux calculus of first order predicate logic. Furthermore, we give polynomial space algorithms for certain sublanguages. 1 Introduction Concept description languages of the klone family are a means of expressing taxonomical knowledge by describing hierarchies of concepts [1, 2, 4, 6, 11]. Concepts are described as specializations of other concepts and by the values of attributes (socalled roles). In contrast to earlier knowledge representation formalisms like frames and semantic networks, klone languages have the advantage of a Tarski style declarative semantics th...
Reasoning with Individuals in Concept Languages
 Data and Knowledge Engineering
, 1994
"... 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 expre ..."
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Cited by 71 (2 self)
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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...
Subsumption Algorithms for Concept Languages
, 1990
"... We investigate the subsumption problem in logicbased knowledge representation languages of the klone family and give decision procedures. All our languages contain as a kernel the logical connectives conjunction, disjunction, and negation for concepts, as well as role quantification. The algorithm ..."
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Cited by 66 (6 self)
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We investigate the subsumption problem in logicbased knowledge representation languages of the klone family and give decision procedures. All our languages contain as a kernel the logical connectives conjunction, disjunction, and negation for concepts, as well as role quantification. The algorithms are rulebased and can be understood as variants of tableaux calculus with a special control strategy. In the first part of the paper, we add number restrictions and conjunction of roles to the kernel language. We show that subsumption in this language is decidable, and we investigate sublanguages for which the problem of deciding subsumption is PSPACEcomplete. In the second part, we amalgamate the kernel language with feature descriptions as used in computational linguistics. We show that feature descriptions do not increase the complexity of the subsumption problem. Contents 1 Introduction 3 2 Concept Languages 7 3 Checking Satisfiability 10 4 PSPACEComplete Languages 13 4.1 Satisf...