Robustness of cooperation on scale-free networks in the evolutionary prisoner's dilemma game

We have studied the robustness of cooperation on scale-free (SF) networks in the prisoner's dilemma game under different attack strategies. Although previous works have demon- strated that increasing heterogeneity constitutes higher levels of cooperation, we elaborated on this subject further by introducing a parameter α to take into consideration two significant aspects during an attack. We have shown that it is possible to precisely control the cooperation level on SF networks to be robust (α � 0) or fragile (α ≥ 0). Moreover, we studied the evolution on SF networks against a different attack strategy, taking over the nodes instead of simply removing the nodes, to address the functional importance of a node. Notably, the network structure re- mains the same during the evolutionary process under this attack strategy, which allows us to investigate the correlation between the functional significance and survival of cooperation. Our results highlight the underlying mechanism of cooperation behavior on SF networks and have several important implications for public health and networks security. Copyright c EPLA, 2014