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Abstract : |
We explore techniques for maintaining consistency in reasoning when employing dynamic hierarchical task decompositions. In particular, we consider the di-culty of maintaining consistency when an agent nonmonotonically modi es an assumption in one level of the task hierarchy and that assumption depends upon potentially dynamic assertions higher in the hierarchy. The hypothesis of our work is that reasoning maintenance can be extended to hierarchical systems such that consistency is maintained across all levels of the hierarchy. We introduce two novel extensions to standard reason maintenance approaches, assumption justi cation and dynamic hierarchical justication, both of which provide the necessary capabilities. The key dierence between the two methods is whether a particular assumption (assumption justication) or an entire level of the hierarchy (dynamic hierarchical justi-cation) is disabled when an inconsistency is found. Our investigations suggest that dynamic hierarchical justi cation has advantages over assumption justication, especially when the task decomposition is wellconstructed. Agents using dynamic hierarchical justi cation also compare favorably to agents using less complete methods for reasoning consistency, improving the reactivity of hierarchical architectures while eliminating the need for knowledge that otherwise would be required to maintain reasoning consistency., |
