The influence of extortion strategies on the evolution of cooperation in the scale-free network

Abstract

Extortion strategies can unilaterally transcend any opponent’s expected payoffs and promote cooperative behaviors in an iterated prisoner’s dilemma game. However, extortion strategies have the evolutionary instability if the players game with uniform structure. In this paper, we study the influence of extortion on the evolution of cooperation in the scale-free network with the player’s game payoffs calculated by average payoffs and the strategy update rule according to the replicator dynamics rule. Firstly, we study the stability of evolutionary game results after introducing the extortion strategy and the influence of evolution extortion on cooperation. In addition, we compare the results of our model with the donation games of the accumulated payoff in the BA networks. Moreover, we study the influence of the model parameters on game results. The results show that extortion can form long-term stable relationships with neighbors and the average payoffs’ inhibiting effect of cooperative behaviors disappear after introducing the extortion strategies in the scale-free network. The smaller value of the extortion actor and the benefit factor have a greater effect on the stability density of the strategies but the initial strategy density does not.