Spatial prisoner's dilemma optimally played in small-world networks

TL;DR

This paper studies how cooperation emerges in spatial prisoner's dilemma games played on various network topologies, finding small-world networks optimize the spread of cooperation and may explain their prevalence in real systems.

Contribution

It demonstrates that small-world networks are optimal for propagating cooperation in spatial prisoner's dilemma, revealing a potential reason for their natural emergence.

Findings

Small-world networks facilitate faster cooperation spread.

Small-world topology is optimal among tested networks.

Results suggest self-organization of small-world properties in real networks.

Abstract

Cooperation is commonly found in ecological and social systems even when it apparently seems that individuals can benefit from selfish behavior. We investigate how cooperation emerges with the spatial prisoner's dilemma played in a class of networks ranging from regular lattices to random networks. We find that, among these networks, small-world topology is the optimal structure when we take into account the speed at which cooperative behavior propagates. Our results may explain why the small-world properties are self-organized in real networks.