| Abstract: | Revision can be seen as any operation which turns a cognitive state CSt into a subsequent cognitive state CSt'. Two kinds of change can be considered: in the “belief change” case, the cognitive states represent beliefs on a world; they are revised in response to the getting of new information about a static world. In the “world change” case, the cognitive states represent known facts on a real world; they are revised in response to change in this dynamic world. We focus in the following on world change case and propose a way to keep up to date with a dynamic world. Reasoning about change requires predicting how the world will change along time. In absence of a predictive model of evolution, the commonsense law of inertia has been currently used and justifies the minimal change approach to the frame problem. We propose here to use an explicit transition model, which will be used as a predictive evolution model. Dean and Kanazawa propose to use a probabilistic model of persistence and causation. We propose in this paper to use a symbolic model of transition by directly encoding expectations. In the first two sections, we describe the formalism that we propose to explicitly encode the transition model and its axiomatisation. We give then a formal definition of the revision operation using a transition model and discuss what can be a contraction operation in the context of world change. an illustrative example is presented and in the last section, our approach is compared to other related works. © 1994 John Wiley & Sons, Inc. |
