Instability of group formation through indirect reciprocity under imperfect information and implementation error

TL;DR

This paper investigates how group formation via indirect reciprocity is affected by imperfect information and errors, revealing instability and the formation of multiple groups under different assessment rules.

Contribution

It numerically analyzes the stability of group formation under imperfect conditions, extending understanding beyond perfect information scenarios.

Findings

Many exclusive groups form under the JUDGING rule with perfect information.

Group stability decreases with increasing information imperfection and errors.

Different assessment rules influence the number and stability of groups.

Abstract

Indirect reciprocity is a key mechanism behind the evolution of cooperation. Oishi et al. analytically showed the formation of two exclusive groups under the KANDORI assessment rule in the case of perfect information and no implementation error, regardless of the population size $N$. Here, we numerically show the formation of many exclusive groups under the JUDGING assessment rule in the same case. Introducing degrees of exclusive groups, we numerically examine the stability of the group formation under imperfect information and implementation error.