Emergence of Altruistic Behavior Based on Game Involves Reputation and Future Expectation in Complex Networks

摘要

We study the altruistic behavior on spatial small-world network and scale-free network in the framework of game theory, by establishing a mechanism based on reputation and future expectation. Each player interacts with his immediate neighbors can follow two strategies: cooperation or defection. Reputation and discount factor are respectively introduced to describe the information of players' historical behavior and the future expectation of players. Players not only consider current payoff but also care about future payoff when they employ strategy. Simulations and analysis show players choose cooperation voluntarily for the purpose of payoff-maximizing as long as the benefit-to-cost ratio is big enough. The level of convergence average reputation of group does not rely on the level of initial average reputation of group absolutely. Group can converge to full cooperation even though the initial average reputation of group is small. In a certain interval, a slight increase of the initial average reputation of group can effectively enhance the level of cooperation. Although the non-subjective factors prevent cooperation from emerging, complex network has a certain ability to resist the disturbance. The cooperation state in scale-free network is more stable than that in small-world network. Concentrating on the situation of group state changing from cooperative to defective, dynamic spatial patterns of small-world network show long-range connections are the main reason for the emergence of new defective cluster. Reasonable network randomness is in favor of motivating altruistic behavior. In scale-free network, heterogeneity makes players converge to three states: full cooperation, full defection and reputation oscillate in a specific domain with particular mode. A small amount of players with large degree and high reputation and a large number of players with small degree and low reputation restrict each other, which enable group can converge to a state between full cooperation and full defection. In addition, heterogeneity has no effect on promoting behavior spread under the mechanism against the common belief.