AAAI Publications, Twelfth International Conference on the Principles of Knowledge Representation and Reasoning

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Forgetting Revisited
Yan Zhang, Yi Zhou

Last modified: 2010-04-27


In this paper, we propose an alternative notion, called weak forgetting, of forgetting a set of predicates in a first-order theory. One important feature of this new notion is that the result of weak forgetting is always first-order expressible. In contrast, this is not the case for the traditional notion of forgetting, called strong forgetting, introduced by Lin and Reiter. As a consequence, these two notions are not exactly the same. Interestingly, we prove that they coincide when the result of strong forgetting is first-order expressible. We also present a representation theorem to characterize weak forgetting from different aspects.


forgetting, first-order logic

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