Description logic
Description Logics (Engl. Description logics ) sometimes called terminological logics are a family of languages knowledge representation . On the one hand, the name should clarify the primary purpose of describing a section of the world with its objects and their relationships to one another. On the other hand, it should become clear that, unlike their predecessors, frames and semantic networks are based on formal logic.
Most description logics are fragments of first order predicate logic and are closely related to modal logic . Many description logics can even be viewed as direct notation variants of known modal logics. An important difference to predicate logic, however, is that many descriptive logic languages are decidable . This allows to infer a description logic, i. H. derive implicit knowledge by inferring from a knowledge base .
In formal terms, a description logic is usually divided into three parts: a concept language or description language , in which the means of expression that are allowed for the formulation of facts are specified, a terminological formalism (the TBox) and an assertional formalism (the ABox). The TBox contains the knowledge about the concepts of the domain , i.e. the terminological knowledge. This defines which classes of objects exist in the domain and which properties they have. In the simplest case, it is a taxonomy of concepts, for example that the set of elephants is a subset of mammals. The ABox, on the other hand, contains the knowledge about a specific instance of a domain. It contains facts about individuals and their properties and their relationships with one another. In this sense it represents the state of the modeled world. A frequently made assumption is that the terminological knowledge in the TBox is fixed and does not or only rarely changes, while the assertional knowledge is subject to more frequent or even constant changes. What is meant is that elephants will always be mammals too, but the number of living elephants is constantly changing.
Description logics become important in connection with ontologies and the Semantic Web . Ontology languages such as DAML + OIL and OWL have - just like description logics - a well-defined syntax which can be mapped to the description logic SHOIN (D), for example. With the description logic as a basis, ontologies can therefore be used to determine what is essential for the use of ontologies in the Semantic Web.
Another application can be found in the area of feature oriented programming , where description logics are used to describe software configurations.
The emergence of the name “description logic” can be dated to the early 1980s. Earlier names are (chronologically):
- Terminological systems,
- Terminological logics,
- Concept languages.
The first description logic-based system was KL-ONE (1985). Other systems followed, including LOOM (1987), BACK (1988), KRIS (1991), CLASSIC (1991), FaCT (1998), RACER (2001) and most recently KAON 2 (2005).
literature
- F. Baader , D. Calvanese, DL McGuiness, D. Nardi, PF Patel-Schneider: The Description Logic Handbook: Theory, Implementation, Applications . Cambridge University Press, Cambridge, UK, 2003. ISBN 0-521-78176-0
- Pascal Hitzler, Markus Krötzsch, Sebastian Rudolph, York Sure: Semantic Web. Basics . Springer, Berlin et al. 2008, ISBN 978-3-540-33993-9 .
Web links
Individual evidence
- ↑ Klaus Schild. A correspondence theory for terminological logics: Preliminary report. In Proc. of the 12th Int. Joint Conf. on Artificial Intelligence (IJCAI'91), pages 466-471, 1991.