Asking for Information by Evaluating the Communication and Coordination Trade-Off in Multi-Agent POMDPs

This letter concerns decentralized multi-agent systems in which individual agents operate under partial observability and uncertainty, but with the option of invoking inter-agent communication. When information exchange is infeasible or prohibitively expensive-owing to bandwidth limits, energy constraints, or the demands of clandestine operation-one is prevented from continually maintaining a joint belief over the underlying system state. In such cases, the decision of when to request information from others is key. In revisiting the prior work addressing this decision head-on, we see conservative strategies: agents are constrained to act solely on information that is accessible to all, with useful local observations being ignored whenever communication is too costly. Such an approach, though apposite to high-risk settings when consistent decision-making must be guaranteed, can degrade overall performance significantly. We explore how agents may integrate their local information, even when it has not been globally shared, and then communicate only when prudent-we term this an ask-type paradigm. This re-formulation, in which the agents are not compelled to synchronize, leads to a novel method that enables the decentralized execution of a centralized policy by reasoning, at execution time, about whether the cost of exchanging information will be offset by the information’s value. We empirically evaluate our approach across several benchmarks and a case study, assessing in each case its effectiveness in trading between tolerating some loss of coordination and reducing communication costs.