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This paper investigates belief revision where the underlying logic is that governing Horn clauses. It proves to be the case that classical (AGM) belief revision doesn't immediately generalise to the Horn case. In particular, a standard construction based on a total preorder over possible worlds may violate the accepted (AGM) postulates. Conversely, Horn(More)
In the past few years, several approaches for revision (and update) of logic programs have been studied. None of these however matched the generality and elegance of the original AGM approach to revision in classical logic. One particular obstacle is the underlying nonmonotonicity of the semantics of logic programs. Recently however, specific revision(More)
Possible-world semantics are provided for Parikh's relevance-sensitive model for belief revision. Having Grove's system-of-spheres construction as a base, we consider additional constraints on measuring distance between possible worlds, and we prove that, in the presence of the AGM postulates, these constraints characterize precisely Parikh's axiom (P).(More)
We present a logical framework for modeling and reasoning about requirements evolution in the construction of information systems. We illustrate how a suuciently rich meta-level logic can formally and accurately capture intuitive ways of handling incompleteness and inconsistency in requirements and how operators that map between theories of this meta-level(More)
In the present work we examine the causal theory of actions put forward by McCain and Turner [Mc-Cain and Turner, 1995] for determining ramifications. Our principal aim is to provide a charac-terisation of this causal theory of actions in terms of a Shoham-like preferential semantics [Shoham, 1988]. This would have a twofold advantage: it would place McCain(More)