Cooperative multi-agent reinforcement learning (MARL) is making rapid progress for solving tasks in a grid world and real-world scenarios, in which agents are given different attributes and goals, resulting in different behavior through the whole multi-agent task. In this study, we quantify the agent's behavior difference and build its relationship with the policy performance via {\bf Role Diversity}, a metric to measure the characteristics of MARL tasks. We define role diversity from three perspectives: action-based, trajectory-based, and contribution-based to fully measure a multi-agent task. Through theoretical analysis, we find that the error bound in MARL can be decomposed into three parts that have a strong relation to the role diversity. The decomposed factors can significantly impact policy optimization on three popular directions including parameter sharing, communication mechanism, and credit assignment. The main experimental platforms are based on {\bf Multiagent Particle Environment (MPE)} and {\bf The StarCraft Multi-Agent Challenge (SMAC). Extensive experiments} clearly show that role diversity can serve as a robust measurement for the characteristics of a multi-agent cooperation task and help diagnose whether the policy fits the current multi-agent system for a better policy performance.

通过量化角色多样性作为度量多智能体任务特征的因素，我们发现，MARL中的误差限可以分解为3个部分，并且这些分解因素对3个热门方向的政策优化具有显著影响，通过MPE和SMAC平台的实验验证，角色多样性可以作为多智能体协作任务特征的强劲度量，并帮助诊断政策是否适合当前的多智能体系统以实现更好的性能。

通过测量合作多智能体 RL 中角色多样性进行策略诊断