Title: Core Advantage Decomposition for Policy Gradients in Multi-Agent Reinforcement Learning
Primary area: reinforcement learning
Keywords: Deep Learning; Reinforcement Learning; Multi-Agent Systems; Game Theory

Abstract: This work focuses on the credit assignment problem in cooperative multi-agent reinforcement learning (MARL). Sharing the global advantage among agents often leads to insufficient policy optimization, as it fails to capture the coalitional contributions of different agents. Existing methods mainly assign credits based on individual counterfactual contributions, while overlooking the influence of coalitional interactions. In this work, we revisit the policy update process from a coalitional perspective and propose an advantage decomposition method guided by the cooperative game-theoretic core solution. By evaluating marginal contributions of all possible coalitions, our method ensures that strategically valuable coalitions receive stronger incentives during policy gradient updates. To reduce computational overhead, we employ random coalition sampling to approximate the core solution efficiently. Experiments on matrix games, differential games, and multi-agent collaboration benchmarks demonstrate that our method outperforms baselines. These findings highlight the importance of coalition-level credit assignment and cooperative games for advancing multi-agent learning.