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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 156 (16 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.
The FaCT system
 In Proceedings of the International Conference on Automated Reasoning with Analytic Tableaux and Related Methods (TABLEAUX’98), volume 1397 in Lecture Notes in Artificial Intelligence
, 1998
"... Abstract. FaCT is a Description Logic classifier which has been implemented as a testbed for a highly optimised tableaux satisfiability (subsumption) testing algorithm. The correspondence between modal and description logics also allows FaCT to be used as a theorem prover for the propositional moda ..."
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Cited by 151 (15 self)
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Abstract. FaCT is a Description Logic classifier which has been implemented as a testbed for a highly optimised tableaux satisfiability (subsumption) testing algorithm. The correspondence between modal and description logics also allows FaCT to be used as a theorem prover for the propositional modal logics K, KT, K4 and S4. Empirical tests have demonstrated the effectiveness of the optimised implementation and, in particular, of the dependency directed backtracking optimisation. 1
FaCT and iFaCT
 Proceedings of the International Workshop on Description Logics, Linköping, Sweden
, 1999
"... scription Logic (DL) classier which has been implemented as a testbed for a sound and complete tableaux satis ability/subsumption testing algorithm. FaCT's novelty lies in its relatively expressive logic and its highly optimised implementation of the tableaux algorithm. iFaCT is an extension ..."
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Cited by 75 (7 self)
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scription Logic (DL) classier which has been implemented as a testbed for a sound and complete tableaux satis ability/subsumption testing algorithm. FaCT's novelty lies in its relatively expressive logic and its highly optimised implementation of the tableaux algorithm. iFaCT is an extension of FaCT that supports reasoning with inverse roles. The resulting logic is particularly interesting as it no longer has the nite model property. Language The logics implemented in FaCT and iFaCT are both based on ALC R, an extension of ALC to include transitive roles [Sattler, 1996]. For compactness, this logic will be called S (due to its relationship with the proposition multimodal logic S4 (m) [Schild, 1991]). FaCT extends S with a hierarchy of roles and functional roles (attributes) to give SHF, while iFaCT adds inverse roles to give SHIF. The constructs used by the two logics are described in Figure 1, where A is an atomic concept, R and S are roles, C and D are concepts, R is the set of transitive role names and F is the set of functional role names (there is an additional restriction that R and F must be disjoint). The meaning of concepts and roles is given by an interpretation I = ( I
Optimizing Description Logic Subsumption
, 1999
"... Effective optimization techniques can make a dramatic difference in the performance of knowledge representation systems based on expressive description logics. With currentlyavailable desktop computers, systems that incorporate these techniques can effectively reason in description logics with intr ..."
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Cited by 68 (6 self)
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Effective optimization techniques can make a dramatic difference in the performance of knowledge representation systems based on expressive description logics. With currentlyavailable desktop computers, systems that incorporate these techniques can effectively reason in description logics with intractable inference. Because of the correspondence between description logics and propositional modal logic, difficult problems in propositional modal logic can be effectively solved using the same techniques.
Reasoning with Concrete Domains
, 1999
"... Description logics are formalisms for the representation of and reasoning about conceptual knowledge on an abstract level. Concrete domains allow the integration of description logic reasoning with reasoning about concrete objects such as numbers, time intervals, or spatial regions. The importa ..."
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Cited by 64 (11 self)
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Description logics are formalisms for the representation of and reasoning about conceptual knowledge on an abstract level. Concrete domains allow the integration of description logic reasoning with reasoning about concrete objects such as numbers, time intervals, or spatial regions. The importance of this combined approach, especially for building realworld applications, is widely accepted. However, the complexity of reasoning with concrete domains has never been formally analyzed and efficient algorithms have not been developed. This paper closes the gap by providing a tight bound for the complexity of reasoning with concrete domains and presenting optimal algorithms. 1 Introduction Description logics are knowledge representation and reasoning formalisms dealing with conceptual knowledge on an abstract logical level. However, for a variety of applications, it is essential to integrate the abstract knowledge with knowledge of a more concrete nature. Examples of such "co...
Optimising Description Logic Subsumption
 Journal of Logic and Computation
, 1999
"... Effective optimisation techniques can make a dramatic difference in the performance of knowledge representation systems based on expressive description logics. With currentlyavailable desktop computers, systems that incorporate these techniques can effectively reason in description logics with intr ..."
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Cited by 57 (17 self)
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Effective optimisation techniques can make a dramatic difference in the performance of knowledge representation systems based on expressive description logics. With currentlyavailable desktop computers, systems that incorporate these techniques can effectively reason in description logics with intractable inference. Because of the correspondence between description logics and propositional modal logic, difficult problems in propositional modal logic can be effectively solved using the same techniques.
The Design Space of Frame Knowledge Representation Systems
 SRI International Artificial Intelligence
, 1993
"... In the past 20 years, AI researchers in knowledge representation (KR) have implemented over 50 frame knowledge representation systems (FRSs). KR researchers have explored a large space of alternative FRS designs. This paper surveys the FRS design space in search of design principles for FRSs. The FR ..."
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Cited by 49 (8 self)
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In the past 20 years, AI researchers in knowledge representation (KR) have implemented over 50 frame knowledge representation systems (FRSs). KR researchers have explored a large space of alternative FRS designs. This paper surveys the FRS design space in search of design principles for FRSs. The FRS design space is defined by the set of alternative features and capabilities  such as the representational constructs  that an FRS designer might choose to include in a particular FRS, as well as the alternative implementations that might exist for a particular feature. The paper surveys the architectural variations explored by different system designers for the frame, the slot, the knowledge base, for accessoriented programming, and for objectoriented programming. We find that few design principles exist to guide an FRS designer as to how particular design decisions will affect qualities of the resulting FRS, such as its worstcase and averagecase theoretical complexity, its actual...
An Empirical Analysis of Terminological Representation Systems
 Artificial Intelligence
, 1994
"... The family of terminological representation systems has its roots in the representation system klone. Since the development of klone more than a dozen similar representation systems have been developed by various research groups. These systems vary along a number of dimensions. In this paper, we p ..."
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Cited by 45 (2 self)
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The family of terminological representation systems has its roots in the representation system klone. Since the development of klone more than a dozen similar representation systems have been developed by various research groups. These systems vary along a number of dimensions. In this paper, we present the results of an empirical analysis of six such systems. Surprisingly, the systems turned out to be quite diverse, leading to problems when transporting knowledge bases from one system to another. Additionally, the runtime performance between different systems and knowledge bases varied more than we expected. Finally, our empirical runtime performance results give an idea of what runtime performance to expect from such representation systems. These findings complement previously reported analytical results about the computational complexity of reasoning in such systems.
Modal description logics: Modalizing roles
 Fundam. Inform
, 1999
"... 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 term ..."
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Cited by 35 (14 self)
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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., statedependent) and global (i.e., stateindependent) 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 (mosaictype) 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
Modal Logics, Description Logics and Arithmetic Reasoning
 ARTIFICIAL INTELLIGENCE
, 1999
"... We introduce mathematical programming and atomic decomposition as the basic modal (TBox) inference techniques for a large class of modal and description logics. The class of description logics suitable for the proposed methods is strong on the arithmetical side. In particular there may be complex a ..."
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Cited by 30 (3 self)
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We introduce mathematical programming and atomic decomposition as the basic modal (TBox) inference techniques for a large class of modal and description logics. The class of description logics suitable for the proposed methods is strong on the arithmetical side. In particular there may be complex arithmetical conditions on sets of accessible worlds (role fillers). The atomic decomposition technique can deal with set constructors for modal parameters (role terms) and parameter (role) hierarchies specied in full propositional logic. Besides the standard modal operators, a number of other constructors can be added in a relatively straightforward way. Examples are graded modalities (qualified number restrictions) and also generalized quantiers like `most', `n%', `more' and `many'.