Language features for flexible handling of exceptions in information systems
ACM Transactions on Database Systems (TODS)
On the complexity of propositional knowledge base revision, updates, and counterfactuals
Artificial Intelligence
Introducing actions into qualitative simulation
IJCAI'89 Proceedings of the 11th international joint conference on Artificial intelligence - Volume 2
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We develop two specific operators for modifying a knowledge base: Amend updates a knowledge base with a formula, while the complementary operator Forget removes a formula from the knowledge base. The approach differs from other belief change operators in that the definition of the operators is compositional with respect to the sentence added or removed. For example, Forget applied to a conjunction is defined to be the union of Forget applied to the individual conjuncts. In some cases the resulting approach has better complexity characteristics than other operators; however, this is at the expense of irrelevance of syntax and other of the Katsuno-Mendelzon update postulates. Alternately, we achieve full irrelevance of syntax if the sentence for update is replaced by the disjunction of its prime implicants and conversely the sentence for removal is replaced by the conjunction of its prime implicates.