The emergence of cooperation via Q-learning in spatial donation game

Abstract Decision-making often overlooks the feedback between agents and the environment. Reinforcement learning is widely employed through exploratory experimentation to address problems related to states, actions, rewards, decision-making in various contexts. This work considers a new perspective, where individuals continually update their policies based on interactions with the spatial environment, aiming to maximize cumulative rewards and learn the optimal strategy. Specifically, we utilize the Q-learning algorithm to study the emergence of cooperation in a spatial population playing the donation game. Each individual has a Q-table that guides their decision-making in the game. Interestingly, we find that cooperation emerges within this introspective learning framework, and a smaller learning rate and higher discount factor make cooperation more likely to occur. Through the analysis of Q-table evolution, we disclose the underlying mechanism for cooperation, which may provide some insights to the emergence of cooperation in the real-world systems.