Towards Generalized Rule-based Updates

Recent work on rule-based updates provided new frameworks for updates in more general knowledge domains [Marek and Truszczriski, 1994; Baral, 1994; Przymusinski and Turner, 1995]. In this paper, we consider a simple generalization of rule-based updates where incomplete knowledge bases are allowed and update rules may contain two types of negations. It turns out that previous methods cannot deal with this generalized rule-based update properly. To overcome the difficulty, we argue that necessary preferences between update rules and inertia rules must be taken into account in update specifications. From this motivation, we propose prioritized logic programs (PLPs) by adding preferences into extended logic programs [Gelfond and Lifschitz, 1991]. Formal semantics of PLPs is provided in terms of the answer set semantics of extended logic programs. We then show that the procedure of generalized rule-based update can be formalized in the framework of PLPs. The minimal change property of the update is also investigated.

Authors

• Yan Zhang School of Computer Science, Hubei University
• Norman Y Foo

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