907052.fig.004a
(a)
907052.fig.004b
(b)
907052.fig.004c
(c)
907052.fig.004d
(d)
Figure 4: Snapshots of typical distributions of cooperators (white), defectors (black), and empty sites (green) on the square lattice for different values of when , , and : (a) ; (b) ; (c) ; (d) .