Figure 8. Impact of the time scale relation on the equilibrium fractions of cooperators in the -plane for additive prisoner's dilemma games (): a lattices and b scale-free networks.

The limit recovers the neutral process (no interactions) whereas for individuals hardly update their strategies. Thus, in both of the two limiting cases the fraction of cooperators remains at the initial value of . For both types of population structures there exists an intermediate that leads to an optimal level of cooperation. On lattices the support for cooperation is strongest if interactions and strategy updates occur at equal rates, , but on scale-free networks more frequent updates than interactions are even more beneficial, . Parameters and averaging technique are as in the caption to Figure 3.