Combining Policy Gradients with Quality-Diversity in Cooperative Multi-Agent Reinforcement Learning
Quality-Diversity (QD) methods combined with policy gradients have shown strong performance in single-agent reinforcement learning, but extending them to multi-agent settings introduces challenges from partial observability and agent interactions. We propose MAPGA-ME, a multi-agent extension of PGA-MAP-Elites that integrates policy gradient updates into MAP-Elites for cooperative control. Our results show that directly transferring policy gradient mechanisms from single-agent QD does not consistently improve performance in multi-agent environments. In particular, a design choice effective in single-agent settings becomes less suitable under decentralized, partially observable conditions. Across multiple configurations, we identify key factors affecting the effectiveness of policy gradient-based QD in multi-agent learning, providing practical guidance for adapting these methods.