Reusing Past Plans in Distributed Planning

This paper describes plan reuse in multiagent domains. In distributed planning, a plan is created by distributed centers of planner agents that have their own viewpoints. Plan reuse where a past plan result is reused for the new problem was proposed for single-agent planning and can achieve efficient planning. A special issue for applying it to distributed planning is that, even if the local agent thinks that the new problem is identical to a past problem, other agents may have quite different goals. Another issue is to realize efficient distributed planning, like in a single-agent case. This paper shows that the past plan can be reused regardless of other agents’ goals under the assumption that the initial state has only "infacts." A generated plan and related information are stored as a plan template so that an agent can reuse it in future planning. This information includes generated plans, subgoals, non-local effects that may affect or be affected by other agents’ plans, and their conflict resolution methods that were actually used. An agent can create a plan efficiently using a template, because it can skip a part of planning actions, detect conflicts in an early stage, and reduce communication costs. First, this paper presents the planning-with-reuse framework. Then how plan templates are created and reused is also illustrated using some block world examples. Finally, we experimentally show that efficient distributed planning can be achieved.