Network flow of mobile agents enhances the evolution of cooperation

¹ Department of Mathematical and Systems Engineering, Shizuoka University - Hamamatsu 432-8561, Japan
² Department of Information Technology, Okayama University - Okayama 700-8530 Japan
³ Department of Mechanical Engineering, Shizuoka University - Hamamatsu 432-8561, Japan

Received: 22 January 2018
Accepted: 27 February 2018

Abstract

We study the effect of contingent movement on the persistence of cooperation on complex networks with empty nodes. Each agent plays the Prisoner's Dilemma game with its neighbors and then it either updates the strategy depending on the payoff difference with neighbors or it moves to another empty node if not satisfied with its own payoff. If no neighboring node is empty, each agent stays at the same site. By extensive evolutionary simulations, we show that the medium density of agents enhances cooperation where the network flow of mobile agents is also medium. Moreover, if the movements of agents are more frequent than the strategy updating, cooperation is further promoted. In scale-free networks, the optimal density for cooperation is lower than other networks because agents get stuck at hubs. Our study suggests that keeping a smooth network flow is significant for the persistence of cooperation in ever-changing societies.