Reference: Washington, R. & Hayes-Roth, B. Abstraction Planning in Real-Time. KSL, March, 1990.
Abstract: An effective real-time planner must adapt to changes in the world, in its goals, and in the available time. In addition, the planner should adapt to these changes within the given time constraints. Because of limited resources, the planner may not be able to construct complete, executable plans. In such cases, the planner should be able to use partially-specified plans. We have developed an approach to real-time planning and replanning that uses multiple levels of abstraction. Planning at each level is viewed as search. Steps in an abstract plan are refined to provide goals for the lower- level searches. The plans may be incomplete in either dimension: the search within any given level may not reach the goal, and the plan may not be refined completely to the lowest level of abstraction. These ideas are being implemented in the Guardian system for intensive-care monitoring.