Making new connections towards cooperation in the prisoner's dilemma game

¹  Research Institute for Technical Physics and Materials Science - P.O. Box 49, H-1525 Budapest, Hungary, EU
²  Faculty of Natural Sciences and Mathematics, University of Maribor - Koroška cesta 160, SI-2000 Maribor, Slovenia, EU
³  Faculty of Natural Sciences, Szeged University - H-6720 Szeged, Hungary, EU

Corresponding author: szolnoki@mfa.kfki.hu

Received: 22 August 2008
Accepted: 27 October 2008

Abstract

Evolution of cooperation in the prisoner's dilemma game is studied where initially all players are linked via a regular graph, having four neighbors each. Simultaneously with the strategy evolution, players are allowed to make new connections and thus permanently extend their neighborhoods, provided they have been successful in passing their strategy to the opponents. We show that this simple coevolutionary rule shifts the survival barrier of cooperators towards high temptations to defect and results in highly heterogeneous interaction networks with an exponential fit best characterizing their degree distributions. In particular, there exist an optimal maximal degree for the promotion of cooperation, warranting the best exchange of information between influential players.