Showing papers by "Paul Morris published in 1990"
Proceedings Article•
29 Jul 1990TL;DR: In this article, a probabilistic approach to non-monotonic reasoning is described, which combines the principle of infinitesimal probabilities with that of maximum entropy, and which sanctions inferences similar to those produced by minimizing abnormalities.
Abstract: This paper describes a probabilistic approach to nonmonotonic reasoning which combines the principle of infinitesimal probabilities with that of maximum entropy, and which sanctions inferences similar to those produced by the principle of minimizing abnormalities. The paper provides a precise formalization of the consequences entailed by a defeasible knowledge base, develops the computational machinery necessary for deriving these consequences, and compares the behavior of the maximum entropy approach to those of Ɛ-semantics ([Pearl 89a]) and rational closure ([Lehmann 89]).
55 citations
01 Jan 1990
TL;DR: The method uses knowledge about exclusive-or relationships in the domain to determine which facts are relevant to particular goals and is used to assist in the selection of which goal to work on next.
Abstract: We describe a method for increasing the efficiency of the search process in automatic planning. The method uses knowledge about exclusive-or relationships in the domain to determine which facts are relevant to particular goals. This information in turn is used to assist in the selection of which goal to work on next. Rather than being supplied by the user, the exclusive-or relationships are extracted directly from an analysis of the planning operators.
10 citations
Proceedings Article•
29 Jul 1990TL;DR: Methods for identifying operator preconditions that need not be expanded further are introduced and are proved to be admissible, that is, they will not cause a solution to be missed when one exists.
Abstract: We introduce methods for identifying operator preconditions that need not be expanded further. The methods are proved to be admissible, that is, they will not cause a solution to be missed when one exists. In certain cases, the methods also identify operator reformulations that increase the number of nonexpandable preconditions. This approach provides effective loop control in common situations. Moreover, the computation required can be performed during a precompilation of the operators in a domain; thus, there is no significant additional run-time overhead during planning.
6 citations
01 Sep 1990
TL;DR: A prototype planning/replanning system that incorporates TMS technology in the plan structure to support efficient backtracking in support of replanning in the context of violated or retracted plan assumptions is described.
Abstract: : The objective of this project was to explore the usefulness of incorporating truth maintenance system (TMS) technology into the design of planning systems. In particular the research was aimed at exploitation of dependency-directed back-tracking in planning search and plan repair, as well as the development of mechanisms enabling use of revokable assumptions about the external world to support replanning in dynamic environments. This report describes a prototype planning/replanning system that incorporates TMS technology in the plan structure to support efficient backtracking in support of replanning in the context of violated or retracted plan assumptions. Techniques for reducing planning search using domain knowledge are also described in the report. The six appendices describe the underlying research contributing to the design of the prototype system. Keywords: Truth maintenance, Planning search, Replanning, Nonmonotonic reasoning, Defeasible reasoning.
6 citations