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The role of the network of contacts in the evolution of cooperation
Francisco C. Santos
Apartado 1329 P-1009-001
Lisboa, Portugal


We have studied the evolution of cooperation in the framework of evolutionary game theory, using the prisoner's dilemma and the snowdrift game in populations in which players are placed on the vertices and their contacts correspond to the edges of graphs. In contrast with previous results we found that correlations between individuals, generated via growth and preferential attachment rules, provide an entirely new regime where cooperation becomes the dominating strategy for the entire range of parameters of both games.


cooperation, evolutionary game theory, complex networks


  1. Santos, F.C., Pacheco, J.M.. Scale-Free Graphs provide a Unifying Framework for the Emergence of Cooperation, Phys .Rev. Lett, . In press.
  2. Dorogotsev, S.N., Mendes, J.F.F.. (2003) Evolution of Networks: From Biological Nets to the Internet and WWW. Oxford University Press.
  3. Hofbauer, J., Sigmund, K.. (1998) Evolutionary Games and Population Dynamics. Cambridge Univ. Press.