FLECS - PLANNING WITH A FLEXIBLE COMMITMENT STRATEGY

There has been evidence that least-commitment planners can efficiently handle planning problems that involve difficult goal interactions. Th is evidence has led to the common belief that delayed-commitment is th e ''best'' possible planning strategy. However, we recently found evid ence that eager-commitment planners can handle a variety of planning p roblems more efficiently, in particular those with difficult operator choices. Resigned to the futility of trying to find a universally succ essful planning strategy, we devised a planner that can be used to stu dy which domains and problems are best for which planning strategies. In this article we introduce this new planning algorithm, FLECS, which uses a FLExible Commitment Strategy with respect to plan-step orderin gs. It is able to use any strategy from delayed-commitment to eager-co mmitment. The combination of delayed and eager operator-ordering commi tments allows FLECS to take advantage of the benefits of explicitly us ing a simulated execution state and reasoning about planning constrain ts. FLECS can vary its commitment strategy across different problems a nd domains, and also during the course of a single planning problem. F LECS represents a novel contribution to planning in that it explicitly provides the choice of which commitment strategy to use while plannin g. FLECS provides a framework to investigate the mapping from planning domains and problems to efficient planning strategies.