Spatial snowdrift game in heterogeneous agent systems with co-evolutionary strategies and updating rules*
Xia Hai-Jiang, Li Ping-Ping, Ke Jian-Hong†, Lin Zhen-Quan
       
The equilibrium cooperation frequency f c as a function of the cost-to-benefit ratio r at ν T = 36. Each f c exhibits a discontinuous steplike structure for an arbitrary composition f a 0. And the value of f c is independent of f a 0 in the range of 1/2 < r < 1.