The emergence of stable cooperators in heterogeneous networked systems

Many real networked systems present the power-law degree distribution and display the scale-free feature. In this paper, we study the emergence of stable cooperators in the evolutionary game of scale-free networks with various degree exponents. Our investigations show that a heterogeneous network with small degree exponent promotes the emergence of stable cooperators, since the cooperative hubs with high degree can efficiently protect themselves from the invasion of defectors for high temptation. Moreover, the coexistence range of cooperators and de fectors is widening as the network becomes heterogeneous, in which individuals are willing to hold onto pure cooperation or defection strategies.