This paper introduces an abductive framework for updating knowledge bases represented by extended disjunctive programs. We first provide a simple transformation from abductive programs to update programs which are logic programs specifying changes on abductive hypotheses. Then, extended abduction, which was introduced by the same authors as a generalization of traditional abduction, is computed by the answer sets of update programs. Next, different types of updates, view updates and theory updates are characterized by abductive programs and computed by update programs. The task of consistency restoration is also realized as special cases of these updates. Each update problem is comparatively assessed from the computational complexity viewpoint. The result of this paper provides a uniform framework for different types of knowledge base updates, and each update is computed using existing procedures of logic programming.
Decker provides an abductive procedure for computing both user updates and schema updates in normal logic programs. User updates corresponds to view updates, while schema updates consider updating a theory with a rule. The procedure is top-down and works correctly for locally stratified programs. Studies @cite_50 @cite_52 @cite_19 characterize belief update revision based on normal abduction in monotonic propositional theories. These approaches are the so-called interpretation updates'' and compute updates in terms of individual models of a theory. This is in contrast to our theory updates which computes updates directly by a program.
@cite_19 @cite_52 @cite_50
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This paper introduces techniques for updating knowledge bases represented in extended logic programs. Three different types of updates, view updates, theory updates, and inconsistency removal, are considered. We formulate these updates through abduction, and provide methods for computing them with update programs. An update program is an extended logic program which specifies changes on abductive hypotheses, then updates are computed by the U-minimal answer sets of an update program. The proposed technique provides a uniform framework for these different types of updates, and each update is computed using existing procedures of logic programming. This paper proposes a method of nonmonotonic theory change. We first introduce a new form of abduction that can account for observations in nonmonotonic situation. Then we provide a framework of autoepistemic update, which describes nonmonotonic theory change through the extended abductive framework. The proposed update semantics is fairly general and provides a unified framework for various update semantics such as first-order update, view update of databases, and contradiction removal of nonmonotonic theories. The Katsuno and Mendelzon theory of belief update has been proposed as a reasonable model for revising beliefs about a changing world. However, the semantics of update relies on information which is not readily available. We describe an alternative semantical view of update in which observations are incorporated into a belief set by: a) explaining the observation in terms of a set of plausible events that might have caused that observation; and b) predicting further consequences of those explanations. We also allow the possibility of conditional explanations. We show that this picture naturally induces an update operator under certain assumptions. However, we argue that these assumptions are not always reasonable, and they restrict our ability to integrate update with other forms of revision when reasoning about action. This paper describes a change theory based on abductive reasoning. We take the AGM postulates for revisions, expansions and contractions, and Katsuno and Mendelzon postulates for updates and incorporate abduction into them. A key feature of the theory is that presents a unified view of standard change operators and abductive change operators rather than a new and independent change theory for abductive changes. Abductive operators reduce to standard change operators in the limiting cases.