Masuda Naoki
Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
Proc Biol Sci. 2007 Aug 7;274(1620):1815-21. doi: 10.1098/rspb.2007.0294.
Real social interactions occur on networks in which each individual is connected to some, but not all, of others. In social dilemma games with a fixed population size, heterogeneity in the number of contacts per player is known to promote evolution of cooperation. Under a common assumption of positively biased pay-off structure, well-connected players earn much by playing frequently, and cooperation once adopted by well-connected players is unbeatable and spreads to others. However, maintaining a social contact can be costly, which would prevent local pay-offs from being positively biased. In replicator-type evolutionary dynamics, it is shown that even a relatively small participation cost extinguishes the merit of heterogeneous networks in terms of cooperation. In this situation, more connected players earn less so that they are no longer spreaders of cooperation. Instead, those with fewer contacts win and guide the evolution. The participation cost, or the baseline pay-off, is irrelevant in homogeneous populations, but is essential for evolutionary games on heterogeneous networks.
每个人都与一些而非所有其他人相连。在固定人口规模的社会困境博弈中,已知每个参与者的联系数量的异质性会促进合作的进化。在收益结构呈正偏差的常见假设下,社交广泛的参与者通过频繁参与能获得很多收益,并且一旦社交广泛的参与者采用合作策略,这种策略就不可战胜并会传播给其他人。然而,维持社会联系可能成本高昂,这会阻止局部收益呈正偏差。在复制者类型的进化动力学中,研究表明,即使是相对较小的参与成本,也会在合作方面消除异质网络的优势。在这种情况下,社交更多的参与者收益更少,以至于他们不再是合作的传播者。相反,那些联系较少的参与者获胜并引导进化。参与成本或基线收益在同质群体中无关紧要,但对于异质网络上的进化博弈至关重要。