Multiagent Online Planning with Nested Beliefs and Dialogue

The problem of planning with partial observability in the presence of a single agent has been addressed as a contingent or POMDP problem. Since the task is computationally hard, on-line approaches have also been developed that just compute the action to do next rather than full policies. In this work, we address a similar problem but in a multiagent setting where agents share a common goal and plan with beliefs which are about the world and the possibly nested beliefs of other agents. For this, we extend the belief tracking formulation of Kominis and Geffner to the on-line setting where plans are supposed to work for the true hidden state as revealed by the observations, and develop an alternative translation into classical planning that is used within a plan-execute-observeand-replan cycle. Planning is done from the perspective of the agents, and there is a single planning agent in each replanning episode that can change across episodes. We present empirical results and show that interesting agent dialogues arise in this setting where agents collaborate by requesting or volunteering information in a goal-directed manner.