On Equivalence Between Decentralized Policy-Profile Mixtures and Behavioral Coordination Policies in Multi-Agent Systems

Constrained decentralized team problem formulations are good models for many cooperative multi-agent systems. Constraints necessitate randomization when solving for optimal solutions -- our past results show that joint randomization amongst the team is necessary for (strong) Lagrangian duality to hold -- , but a better understanding of randomization still remains. For a partially observed multi-agent system with Borel hidden state and finite observations and actions, we prove the equivalence between joint mixtures of decentralized policy-profiles (both pure and behavioral) and common-information based behavioral coordination policies (also mixtures of them). This generalizes past work that shows equivalence between pure decentralized policy-profiles and pure coordination policies. The equivalence can be exploited to develop results on strong duality and number of randomizations.