Book contents
- Frontmatter
- Contents
- List of contributors
- Preface to the second edition
- Preface
- 1 An Introduction to Description Logics
- Part I Theory
- 2 Basic Description Logics
- 3 Complexity of Reasoning
- 4 Relationships with other Formalisms
- 5 Expressive Description Logics
- 6 Extensions to Description Logics
- Part II Implementation
- Part III Applications
- Appendix: Description Logic Terminology
- Bibliography
- Index
6 - Extensions to Description Logics
Published online by Cambridge University Press: 06 July 2010
- Frontmatter
- Contents
- List of contributors
- Preface to the second edition
- Preface
- 1 An Introduction to Description Logics
- Part I Theory
- 2 Basic Description Logics
- 3 Complexity of Reasoning
- 4 Relationships with other Formalisms
- 5 Expressive Description Logics
- 6 Extensions to Description Logics
- Part II Implementation
- Part III Applications
- Appendix: Description Logic Terminology
- Bibliography
- Index
Summary
Abstract
This chapter considers, on the one hand, extensions of Description Logics by features not available in the basic framework, but considered important for using Description Logics as a modeling language. In particular, it addresses the extensions concerning: concrete domain constraints; modal, epistemic, and temporal operators; probabilities and fuzzy logic; and defaults.
On the other hand, it considers non-standard inference problems for Description Logics, i.e., inference problems that – unlike subsumption or instance checking – are not available in all systems, but have turned out to be useful in applications. In particular, it addresses the non-standard inference problems: least common subsumer and most specific concept; unification and matching of concepts; and rewriting.
Introduction
Chapter 2 introduces the language ALCN as a prototypical Description Logic, defines the most important reasoning tasks (like subsumption, instance checking, etc.), and shows how these tasks can be realized with the help of tableau-based algorithms. For many applications, the expressive power of ALCN is not sufficient to express the relevant terminological knowledge of the application domain. Some of the most important extensions of ALCN by concept and role constructs have already been briefly introduced in Chapter 2; these and other extensions have then been treated in more detail in Chapter 5. All these extensions are “classical” in the sense that their semantics can easily be defined within the model-theoretic framework introduced in Chapter 2. even to undecidable ones), all the Description Logics obtained this way can only be used to represent time-independent, objective, and certain knowledge.
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- Chapter
- Information
- The Description Logic HandbookTheory, Implementation and Applications, pp. 237 - 282Publisher: Cambridge University PressPrint publication year: 2007
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