Priorities on Defaults with Prerequisites, and their Application in Treating Specificity in Terminological Default Logic

Franz BaaderFranz Baader, B. HollunderB. Hollunder

Franz Baader, B. Hollunder
Priorities on Defaults with Prerequisites, and their Application in Treating Specificity in Terminological Default Logic
J. Automated Reasoning, 15:41-68, 1995

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KurzfassungAbstract
In a recent paper we have proposed terminological default logic as a formalism which combines both means for structured representation of classes and objects, and for default inheritance of properties. The major drawback that terminological default logic inherits from general default logic is that it does not take precedence of more specific defaults over more general ones into account. This behaviour has already been criticized in the general context of default logic, but it is all the more problematic in the terminological case where the emphasis lies on the hierarchical organization of concepts. The present paper addresses the problem of modifying terminological default logic such that more specific defaults are preferred. We assume that the specificity ordering is induced by the hierarchical organization of concepts, which means that default information is not taken into account when computing priorities. It turns out that the existing approaches for expressing priorities between defaults do not seem to be appropriate for defaults with prerequisites. Therefore we shall consider an alternative approach for dealing with prioritization in the framework of Reiter's default logic. The formalism is presented in the general setting of default logic where priorities are given by an arbitrary partial ordering on the defaults. We shall exhibit some interesting properties of the new formalism, compare it with existing approaches, and describe an algorithm for computing extensions. In the terminological case, we thus obtain an automated default reasoning procedure that takes specificity into account.
Forschungsgruppe:Research Group: AutomatentheorieAutomata Theory

@article{ BaaderHollunderB-JAR-95,
  author = {F. {Baader} and B. {Hollunder}},
  journal = {J. Automated Reasoning},
  pages = {41--68},
  title = {Priorities on Defaults with Prerequisites, and their Application in Treating Specificity in Terminological Default Logic},
  volume = {15},
  year = {1995},
}