AIM-94-1213-CB PREDICTIVE SUFFICIENCY AND THE USE OF STORED INTERNAL STATE N94- 30564

In all embedded computing systems, some delay exists between sensing and acting. By choosing an action based on sensed data, a system is essentially predicting that there will be no significant changes in the world during this delay. However, the dynamic and uncertain nature of the real world can make these predictions incorrect, and thus a system may execute inappropriate actions. Making systems more reac-tive by decreasing the gap between sensing and action leaves less time for predictions to err, but still provides no prjncipled assurance that they will be correct. Using the concept of predictive s u f i c i e n c y de-scribed in this paper, a system can prove that its predictions are valid, and that it will never execute inappropriate actions. In the context of our CIRCA system, we also show how predictive sufficiency al-lows a system to guarantee worst-case response times to changes in its environment. Using predictive suf-ficiency, CIRCA is able to build real-time reactive control plans which provide a sound basis for per-formance guarantees that are unavailable with other reactive systems