Games, Networks and Self-Organization: Explaining the collective transition to social cooperation

Abstract

The emergence of cooperation among selfish agents that have no incentive to cooperate is a non-trivial phenomenon that has long intrigued biologists, social scientists and physicists. The iterated Prisoner’s Dilemma (IPD) game provides a natural framework for investigating this phenomenon. The spatial version of IPD, where each agent interacts only with their nearest neighbors on a specified connection topology, has been used to  study the evolution of cooperation under conditions of bounded rationality. This talk will explorehow the collective behavior that arises from the simultaneous actions of the agents (implemented by synchronous update) is affected by the connection topology among the interacting agents. The system exhibits three types of collective states, viz., a pair of absorbing states (corresponding to all agents cooperating or defecting, respectively) and a fluctuating state characterized by agents switching intermittently between cooperation and defection. We show that the system exhibits a transition from one state to another simply by altering the connection topology from regular to random, without altering any of the parameters govering the game dynamics, such as temptation payoff or noise. Such topological phase transitions in collective behavior of strategic agents suggest important role that social structure may play in promoting cooperation.