NFO13018901 Intro Network science14307130355李婧雅 with biggest degree defector and others are cooperators. Then watch the invasion hub node x make to cooperative behaviors in the network. We can find, because of high payoff x gets from its cooperative neighbor nodes, these small-degree neighbor nodes will copy its behavior and according to the research, there will be about 80% neighbor nodes changing into defectors after a time. With the fall of the percentage of cooperative neighbor nodes, the node x's payoff will be lower than some big-degree cooperative neighbor nodes and then it will realize the payoff of cooperation is higher than that of defection, so x will turn into cooperator. After that, most of its neighbor nodes will choose cooperation again The above analysis shows hub nodes can effectively resist the invade from defectors 4. Simulation experiment&analysis We use matlab to simulate the cooperative behavior evolutionary in the two different networks and set different values of t to see the change of p. Besides, we compare the result of two networks with different values of T and get some practical summaries 4.1 prisoners'dilemma in the square lattice network For easier calculation, we set R=1, S=P=0. When T>1, the game follows the prisoners'dilemma. We set the size of network is 200*200 and the evolutionary time is 50. Then we'll see the evolutionary game in the situation ofT=1.3, 1.6, 1.9, 4.1.1 simulation resultINFO130189.01 Intro Network Science 14307130355 李婧雅 9 with biggest degree defector and others are cooperators. Then watch the invasion hub node x make to cooperative behaviors in the network. We can find, because of high payoff x gets from its cooperative neighbor nodes, these small-degree neighbor nodes will copy its behavior and according to the research, there will be about 80% neighbor nodes changing into defectors after a time. With the fall of the percentage of cooperative neighbor nodes, the node x’s payoff will be lower than some big-degree cooperative neighbor nodes and then it will realize the payoff of cooperation is higher than that of defection, so x will turn into cooperator. After that, most of its neighbor nodes will choose cooperation again. The above analysis shows hub nodes can effectively resist the invade from defectors. 4. Simulation experiment&analysis We use matlab to simulate the cooperative behavior evolutionary in the two different networks and set different values of T to see the change of  . Besides, we compare the result of two networks with different values of T and get some practical summaries. 4.1 prisoners’ dilemma in the square lattice network For easier calculation, we set R=1, S=P=0. When T>1, the game follows the prisoners’ dilemma. We set the size of network is 200*200 and the evolutionary time is 50. Then we’ll see the evolutionary game in the situation of T=1.3, 1.6, 1.9, 4.1.1 simulation result