DISTRIBUTED GOAL-DIRECTED DYNAMIC PLAN REVISION

We contrast in this article the system demands imposed by brute force, complete replanning, and a new, goal-directed approach called dynamic plan revision (DPR). One of the two processes must be invoked when so me aspects of the environment change and currently existing plans are likely to fail. Complete replanning is conceptually simpler but requir es significantly more computation because it reproduces also those pla n steps that have not been affected by the changes. DPR attempts to mi nimize the scope of replanning and makes to the current plans as small amount of modification as possible. The more rapidly the environment changes, the less practical complete replanning becomes. The issue is even more significant with time-critical applications. DPR uses goal h ierarchies produced at the same time when plans are generated. The pla nning systems has an ''active attitude'' toward the feedback from the environment and takes advantage of all information becoming available during plan execution. We have also developed and implemented a distri buted version of this approach in the domain of Distributed Manufactur ing Operations [N. V. Findler and J. Gao, Data and Know. Eng., 2, 285- 301 (1987); Q. Ge and N. V. Findler, Proc. Austr. Joint Conf. on Art. Int., 439-455 (1988); N. V. Findler and Q. Ge, Int. J. Intell. Syst., 4, 459-470 (1989)]. The relevant algorithms are given in the Appendice s A and B. (C) 1994 John Wiley & Sons, Inc.