A. Borgida. Description Logics are not just for the Flightless-Birds: A New Look at the Utility and Foundations of Description Logics. Technical report, Rutgers University, 1992.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....when constructing queries. Description Logics (DLs) are knowledge representation schemes which have been advocated as suitable frameworks for metadata [4] The hierarchical compositional models provided by a DL have the potential to support complex incremental manipulations of query expressions [6]. The TAMBIS project [1] aims to integrate biological information sources by acting as a mediator and presenting the illusion of a single data source. It achieves this through the use of a conceptual model (the Tambis Ontology [2] which represents the metadata of the underlying data sources ....

A. Borgida. Description Logics are not just for the Flightless-Birds: A New Look at the Utility and Foundations of Description Logics. Technical report, Rutgers University, 1992.

....have a different flavor than the predicate calculus. Description logics comprise natural classes of formulas; not only are they the subject of theoretical investigation within the field of knowledge representation, but they also find use in practical knowledge based systems (Beck et al. 1989; Borgida, 1992; Borgida Patel Schneider, 1992; Brachman et al. 1983; Cohen Hirsh, 1994b; Devanbu et al. 1991; Mays et al. 1987; Patel Schneider, 1989) 1.1. Classic Classic permits constructing certain quantified descriptions that distinguish a particular subset of a domain I of individuals. Classic ....

....the current environment and task at hand. What language should be used to describe an individual We employ the commonly used single representation trick wherein the description of an individual is itself a Classic sentence. This approach is supported by the description logic community (Borgida, 1992; Bobrow Winograd, 1977; Dietterich et al. 1982) in which it is often convenient and desirable to represent concepts and examples using the same language. In fact, Cohen and Hirsh (1994a) note that in many implemented description logics, it is possible to attach an arbitrary description to an ....

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Borgida, A. (1992). Description logics are not just for the flightless-birds: a new look at the utility and foundations of description logics. Preprint.

.... and controlled as part of the system rather than being implemented by users on an ad hoc basis [Mac91a] Borgida has pointed out that one problem with this approach is the difficulty of characterising to users the exact circumstances which will result in incomplete reasoning or intractability [Bor92]. LOOM tackles the intractability aspect of this problem by providing a power level function which allows the user to limit the computational effort expended in seeking expensive types of inferencing [Bri93] however it is admitted to be difficult to precisely characterise the types of ....

....the query expression will then be recognised by the A Box as instances of the concept or relation. 17 It has been shown to be necessary to ignore individuals as role fillers in order to maintain the monotonicity of classification when assertional retractions and redefinitions are permitted [Bor92]. 18 The classification of individuals in terms of the concepts they instantiate. 25 Table 3.6 LOOM query expressions Expression Returns (same as v1 v2) true if v1 and v2 are equivalent (subset v1 v2) true if v1 v2 are sets v1 is a subset of v2 (about I C) true if I is an instance of ....

A. Borgida. Description logics are not just for the flightless-birds: A new look at the utility and foundations of description logics. Unpublished paper, June 1992. Available from: ftp://athos.rutgers.edu/pub/technical-reports/dcs-tr-295.ps.Z.

....Bell Labs Research Murray Hill, NJ, U.S.A. pfps research.bell labs.com 1 Introduction The tradeoff between expressiveness and tractability in Description Logics (DLs) has long been recognised [9] For DL system designers and implementors there are several possible approaches to this problem [3]. These include: ffl (severely) constraining expressiveness so that (Tbox) reasoning can be performed in polynomial time (e.g. Classic [11] ffl using tractable but incomplete reasoning algorithms (e.g. Loom [10] ffl using sound and complete reasoning algorithms for logics with high worst ....

A. Borgida. Description logics are not just for the flightless-birds: A new look at the utility and foundations of description logics. Technical Report DCS-TR-295, New Brunswick Department of Computer Science, Rutgers University, 1992.

.... by their limited expressiveness (Doyle and Patil 1991; MacGregor 1991) and the intractability of their subsumption algorithms (Heinsohn et al. 1994; Speel et al. 1995) 1 This paper addresses both these issues by 1 A desire requirement for sound and complete reasoning is assumed, but see (Borgida 1992) for a discussion of this issue. describing a tableaux subsumption testing algorithm for a relatively expressive DL which, in spite of the logic s worst case complexity, has been shown to perform well in realistic applications. A particularly promising application domain for DLs is in the growth ....

A. Borgida. Description logics are not just for the flightless-birds: A new look at the utility and foundations of description logics. Technical Report DCS-TR295, New Brunswick Department of Computer Science, Rutgers University, 1992.

....C of relation quote is constrained to have non negative values. 2 2.2. Using Classic in the World View An interesting aspect of our approach is the use of the Classic knowledge representation language as part of our data model. Classic is a member of a family of description logic systems (see (Borgida, 1992) for a survey) There are several advantages to using a description logic system as part of the world view component of a global information system. The key advantage is their ability to support extensibility and modifiability of the world view. Although the world view should be 8 relatively ....

Borgida, A. (1992). Description logics are not just for the FLIGHTLESS-BIRDS: A new look at the utility and foundations of description logics. Technical Report DCS-TR-295, Department of Computer Science, Rutgers University.

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