Incorporating specificity into circumscriptive theories

  • James P. Delgrande
  • Torsten H. Schaub
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 861)


We describe an approach whereby specificity notions are introduced into circumscriptive theories. In this approach, a default theory is initially given as a set of strict and defeasible conditionals. By making use of a theory of default conditionals, here given by System Z, we isolate minimal sets of defaults with specificity conflicts. From the specificity information intrinsic in these sets, a propositional theory is specified. By circumscribing a set of “abnormality” propositions, one obtains a nonmonotonic reasoning system in which specificity information is appropriately handled. This notion of specificity subsumes that of property inheritance, and so in this approach a bird will fly (by default) whereas a penguin will not. This work differs from previous work in specifying priorities in circumscription, in that priorities are obtained from information intrinsic in a set of conditionals, rather than assumed to exist a priori. This paper extends earlier work in hybrid nonmonotonic reasoning systems: First, in this previous work specificity issues were addressed with respect to Default Logic. Second, we here augment the approach to allow strict as well as default knowledge.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1994

Authors and Affiliations

  • James P. Delgrande
    • 1
  • Torsten H. Schaub
    • 2
  1. 1.Simon Fraser UniversityBurnabyCanada
  2. 2.Campus de BeaulieuIRISARennes cedexFrance

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