Adding priorities and specificity to default logic

  • Gerhard Brewka
Conference paper

DOI: 10.1007/BFb0021977

Part of the Lecture Notes in Computer Science book series (LNCS, volume 838)
Cite this paper as:
Brewka G. (1994) Adding priorities and specificity to default logic. In: MacNish C., Pearce D., Pereira L.M. (eds) Logics in Artificial Intelligence. JELIA 1994. Lecture Notes in Computer Science (Lecture Notes in Artificial Intelligence), vol 838. Springer, Berlin, Heidelberg

Abstract

Reiter's Default Logic (DL) is one of the most popular formalizations of default reasoning. Nevertheless, the logic has a serious deficiency: the specificity principle, i.e. the commonly accepted idea that in case of a conflict more specific defaults should be preferred over more general ones, is lacking. In this paper we show how this principle can be added to Default Logic. We first present a prioritized version of DL for normal defaults, called PDL. Adapting ideas underlying Geffner and Pearl's conditional entailment we then show how the priorities needed to handle specificity can be defined. This treatment of specificity avoids two serious problems in Pearl's system Z and leads to stronger conclusions than conditional entailment in many cases.

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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Gerhard Brewka
    • 1
  1. 1.Schloss BirlinghovenGMDSankt AugustinGermany

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