Are Multiagent Systems Resilient to Communication Failures?
Identifies a fundamental vulnerability in game-theoretic multiagent control, warning system designers that communication failures can cause catastrophic outcomes even in weakly-coupled systems.
The paper shows that even a single communication failure between weakly-coupled agents can cause arbitrarily-bad system states in multiagent control systems, regardless of how agents adapt. The harm is limited by problem structure, and richer action spaces increase susceptibility.
A challenge in multiagent control systems is to ensure that they are appropriately resilient to communication failures between the various agents. In many common game-theoretic formulations of these types of systems, it is implicitly assumed that all agents have access to as much information about other agents' actions as needed. This paper endeavors to augment these game-theoretic methods with policies that would allow agents to react on-the-fly to losses of this information. Unfortunately, we show that even if a single agent loses communication with one other weakly-coupled agent, this can cause arbitrarily-bad system states to emerge as various solution concepts of an associated game, regardless of how the agent accounts for the communication failure and regardless of how weakly coupled the agents are. Nonetheless, we show that the harm that communication failures can cause is limited by the structure of the problem; when agents' action spaces are richer, problems are more susceptible to these types of pathologies. Finally, we undertake an initial study into how a system designer might prevent these pathologies, and explore a few limited settings in which communication failures cannot cause harm.