Episodic cases and real-time performance in a case-based planning system

摘要

In this article, we discuss COOKIE, an integrated planning, execution, and learning system that operates in the domain of meal planning and preparation. Its episodic representation scheme is used to avoid brittleness in planning, help attain real-time performance, and simplify the case acquisition process. An episodic representation of an event is one that allows reconstruction of the event—all of the actions, when they happened, what facts were true, and so forth. In COOKIE, this is a set of propositions in a temporal logic corresponding to the initial conditions, end conditions, goals, actions, and observations taken during the preparation of a meal. This representation is usable for a range of reasoning tasks: plan generation and projection, plan recognition, explanation, and failure recovery. This representation also promotes efficient real-time performance. The details present in the episode are maintained in the generated plans, providing the necessary information to schedule actions and observations before plan execution begins. We describe how our execution monitor was implemented to take advantage of this information while performing in an efficient manner.