Information-Theoretic Approach to Detect Collusion in Multi-Agent Games

Trevor Bonjour, Vaneet Aggarwal, Bharat Bhargava

Keywords: Collusion, Information Theory, Mutual Information, Multi-Agent Games, Net Influence

Abstract: Collusion in a competitive multi-agent game occurs when two or more agents co-operate covertly to the disadvantage of others. Most competitive multi-agent games do not allow players to share information and explicitly prohibit collusion. In this paper, we present a novel way of detecting collusion using a domain-independent information-theoretic approach. Specifically, we show that the use of mutual information between actions of the agents provides a good indication of collusive behavior. Our experiments show that our method can detect varying levels of collusion in repeated simultaneous games like iterated Rock Paper Scissors. We further extend the detection to partially observable sequential games like poker and show the effectiveness of our methodology.