CLASSIC(ID:3996/cla015)
TSL knowledge representation language
Bell Labs 1989
Related languages
References:
Borgida et al "CLASSIC: A Structural Data Model for Objects" view details
Abstract: CLASSIC is a data model that encourages the description of objects not only in terms of their relations to other known objects, but in terms of a level of intensional structure as well. The CLASSIC language of structured descriptions permits i) partial descriptions of individuals, under an `open world' assumption, ii) answers to queries either as extensional lists of values or as descriptions that necessarily hold of all possible answers, and iii) an easily extensible schema, which can be accessed uniformly with the data. One of the strengths of the approach is that the same language plays multiple roles in the processes of defining and populating the DB, as well as querying and answering. CLASSIC (for which we have a prototype main-memory implementation) can actively discover new information about objects from several sources: it can recognize new classes under which an object falls based on a description of the object, it can propagate some deductive consequences of DB updates, it has simple procedural recognizers, and it supports a limited form of forward-chaining rules to derive new conclusions about known objects. The kind of language of descriptions and queries presented here provides a new arena for the search for languages that are more expressive than conventional DBMS languages, but for which query processing is still tractable. This space of languages differs from the subsets of predicate calculus hitherto explored by deductive databases.
in [ACM] Proceedings of the 1989 ACM SIGMOD International Conference on Management of Data, Portland, OR, May 1989 view details
Bernd Owsnicki-Klewe and Alfred Kobsa "Term Subsumption Languages in Knowledge Representation" view details
Abstract: Term subsumption languages are
knowledge representation formalisms
that employ a formal language with a
formal semantics for the definition of
terms (more commonly referred to as
concepts or classes) and that deduce
whether one term subsumes (is more
general than) another. These formalisms
generally descend from the
ideas presented in KL-One (Brachman
and Schmolze 1985). TSLs are a generalization
of both semantic networks
and frames. One result of the workshop
was to standardize use of the
term terminological logics to describe
these formalisms; term subsumption
languages was chosen as a neutral
term for describing the workshop.
In the last few years, many knowledge
representation systems have
been built using TSLs, including
Krypton (Brachman et al. 1985), KLTwo
(Vilain 1984), NIKL (Robbins
1986; Kaczmarek, Bates, and Robbins
1986), Back (Peltason et al. 1989;
Nebel and vonLuck 1988), Meson
(Edelmann and Owsnicki 1986), SBOne
(Kobsa 1990), Loom (MacGregor
and Bates 1987), Quirk (Bergmann
and Gerlach 1987), and Classic
(Borgida et al. 1989). These systems
go beyond a bare TSL in various
ways: Almost all of them incorporate
assertional languages that enable the
systems to reason about instances of
terms, some of them allow for retraction
of told facts, and so on. The
workshop not only concerned TSLs
but also TSL-based knowledge representation
systems and their use in
larger AI systems.
Outline of the Workshop
The workshop was designed to encourage
discussion. To aid this approach,
no formal talks were presented, and
no proceedings is being produced.
For a large portion of the workshop,
the attendees were divided into
working groups of 7 to 15 participants.
Each working group was devoted to
in-depth discussion of particular
topics. Moderators were chosen to
keep the discussions flowing and on
track and were assisted by preselected
discussants who presented short position
statements. Ample time was left
for intensive discussion, although
several of the discussions could not
be completed within their allotted
time and had to be continued in
the evening. Moderators reported
the results of the working groups in
plenary sessions that also allowed
for further discussion of the topics
covered.
in AI Magazine Summer 1990 view details
Brachman et al "Living with CLASSIC: When and How to Use a KL-ONE-Like Language" pp401-456 view details
Abstract: CLASSIC is a recently-developed knowledge representation system that follows the paradigm originally set out in the KLONE system: it concentrates on the definition of structured concepts, their organization into taxonomies, the creation and manipulation of individual instances of such concepts, and the key inferences of subsumption and classification. Rather than simply presenting a description of CLASSIC, we complement a brief system overview with a discussion of how to live within the confines of a limited object-oriented deductive system. By analyzing the representational strengths and weaknesses of CLASSIC, we consider the circumstances under which it is most appropriate to use (or not use) it. We elaborate a knowledge-engineering methodology for building KLONE-style knowledge bases, with emphasis on the modeling choices that arise in the process of describing a domain. We also address some of the key difficult issues encountered by new users, including primitive vs. defined concepts, and differences between roles and concepts, as well as representational "tricks-of-the-trade,'' which we believe to be generally useful. Much of the discussion should be relevant to many of the current systems based on KLONE.
in John Sowa, ed., Principles of Semantic Networks: Explorations in the representation of knowledge , Morgan-Kaufmann: San Mateo, California, 1991 view details
McGuinness, Deborah L. The CLASSIC Knowledge Representation System: Implementation, Applications, and Beyond. 80-86 view details
in Bernhard Nebel, Kai von Luck, Christof Peltason (Eds.): Proceedings of the International Workshop on Terminological Logics, DFKI-D-91-13, 1991. Also published as KIT Report and IWBS Report 184 view details
Patel-Schneider et al "The CLASSIC Knowledge Representation System: Guiding Principles and Implementation Rationale" pp108-113 view details
Abstract: Our work on the CLASSIC knowledge representation system covers a broad range from theory to practice. While CLASSIC was implemented primarily to provide a simple, easy to learn and use, locally available tool for a relatively limited set of applications, it has a substantial theoretical foundation, based on a formal "terminological'' logic. The logical foundation provides the semantics of a term description language, which is used to define structured concepts and make assertions about individuals in a knowledge base. These concepts and individuals are organized into a generalization hierarchy by classification and subsumption algorithms. The CLASSIC system explores the expressiveness vs. tractability tradeoff, driven by concerns of usefulness and usability in several real applications. Within this context, it embodies our views of what a knowledge representation system should be: useful, comprehensible and usable, predictable, non-subvertable, and at bottom, based on a formal logic.
The CLASSIC knowledge representation system has been designed and implemented at AT&T Bell Laboratories over the last several years. CLASSIC has its roots in at least a dozen years of work on theory and implementation of "terminological'' knowledge representations. The main reason for building an implementation was to provide a locally available tool to support several classes of applications that were important at AT&T. Among our main concerns were leverage on these applications---that is, the system had to be useful in a real practical context---it had to be understandable by non-experts---that is, really usable and it had to be reliable and predictable .
CLASSIC is based on a formal logic, research on which proceeds in parallel with implementation and use, and there has been much interplay between these two sides of the work. We have now had significant practical experience with the first release of the system, and are substantially into a second version. CommonLisp and C implementations of CLASSIC exist and are in use in applications. The system is fully documented and the CommonLisp version is available to universities for research use.
in ACM SIGART Bulletin 2(3) June 1991 Special issue on implemented knowledge representation and reasoning systems view details
Resnick, L.A. ; A. Borgida, R.J. Brachman, D.L. McGuinness, P.F. Patel-Schneider, and K.C. Zalondek. CLASSIC description and reference manual for the Common Lisp implementation, version 1.1. Unpublished system manual, 1991 view details
in ACM SIGART Bulletin 2(3) June 1991 Special issue on implemented knowledge representation and reasoning systems view details
Brachman et al, "The CLASSIC Knowledge Representation System or, KL-ONE: The Next Generation" view details
Abstract: CLASSIC is a recently developed knowledge representation (KR) system, based on a view of frames as structured descriptions, with several important inferable relationships, including description classification. While much about CLASSIC is novel and important in its own right, it is especially interesting to consider the system in light of its unusual (for Artificial Intelligence) intellectual history: it is the result of over a decade of research and evolution in representation systems that trace their origins back to work on KLONE, arguably one of the most long-lived and influential approaches to KR in the history of AI. We outline some of the novel contributions of CLASSIC, but pay special attention to its roots, illustrating the maturation of some of the original features of KLONE, and the decline and fall of others. A number of key ideas are analyzed---including the interpretation of frames as descriptions, the classification inference, and the role of a knowledge representation system in a knowledge-based application. The rare traceable relationship between CLASSIC and its ancestor gives us an opportunity to assess progress in a generation of knowledge representation research.
in Proceedings of the 1992 International Conference on Fifth Generation Computer Systems , Tokyo, Japan, 1992 view details
Borgida, A.; Patel-Schneider, P.F. A semantics and complete algorithm for subsumption in the CLASSIC description logic, Journal of Artificial Intelligence Research 1 (1994) 277-308. view details
in Proceedings of the 1992 International Conference on Fifth Generation Computer Systems , Tokyo, Japan, 1992 view details
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