Network flow of mobile agents enhances the evolution of cooperation

TL;DR

This paper investigates how the movement of mobile agents on complex networks influences the persistence and promotion of cooperative behavior, highlighting the importance of network flow and agent mobility.

Contribution

It introduces a model combining agent movement and strategy updating, demonstrating how medium density and movement frequency enhance cooperation in complex networks.

Findings

Medium agent density optimizes cooperation.

Higher movement frequency promotes cooperation.

Scale-free networks have lower optimal densities due to hub trapping.

Abstract

We study the effect of contingent movement on the persistence of cooperation on complex networks with empty nodes. Each agent plays 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.