Changing Roles of Meta-agents in Simulations of The Tragedy of The Common
Keiji Suzuki
suzukj@fun.ac.jp


     Agent based social behavior simulations are research filed that treats complex game situations and examines artificial intelligence. Social dilemmas are one of the complex game situations and suite to
examine the intelligence of agents. In this paper, the Tragedy of the Common, which is one of the social dilemmas, is treated in the agent-based simulation. In this game, players use common limited resources to get the reward. If players behave based on the individual rationality, all players will face to tragedies loosing higher payoff. To avoid such tragedies, players have to make the relationship between other agents to prevent the individual behaviors or change the problem structure, for example, changing the
payoff functions.
     The proposed approach is kind of the changing problem structure. That is, the meta-agent is introduced to control the levy charging to the players. In previous researches, the role of meta-agents is fixed. Because it is important who acts the role of meta-agents in real society, agent based simulation should be provide the decision mechanism that includes the selection of the role.Therefore, it is proposed that role of the meta-agent is treated as one of the activities of the players. Namely, the player will select the role of the meta-agent if the expected revenue exceeds than the expected rewards when the agent acts as the player.
     Another problem for introducing the meta-agent is how to set the plan of the levies charging to the activities of the players. To acquire the plan, co-evolution of levy plan between the agents is prepared.Based on the co-evolutionary acquisition of the levy plan and the decision mechanism including the selection of the role, it will be examined the effects of the interaction between the meta-agents and the agents in the Tragedy of the Common game.