Forgiveness is an Adaptation in Iterated Prisoner's Dilemma with Memory

TL;DR

This paper investigates how forgiveness functions as an adaptive strategy in the iterated Prisoner's Dilemma with memory, especially in heterogeneous environments, challenging previous findings and highlighting the importance of forgiveness in complex social interactions.

Contribution

The study introduces improved and new forgetting strategies, conducts experiments in heterogeneous environments, and demonstrates that forgiveness is a key adaptive strategy in competitive settings.

Findings

Outcome depends on environment type, contrasting previous research.

Forgiving defectors outperform other strategies in heterogeneous environments.

Forgetting strategies vary in effectiveness between homogeneous and heterogeneous settings.

Abstract

The Prisoner's Dilemma is used to represent many real life phenomena whether from the civilized world of humans or from the wild life of the other living. Researchers working on iterated prisoner's dilemma (IPD) with limited memory inspected the outcome of different forgetting strategies in homogeneous environment, within which all agents adopt the same forgetting strategy at a time. In this work, with the intention to represent real life more realistically, we improve existing forgetting strategies, offer new ones, and conduct experiments in heterogeneous environment that contains mixed agents and compare the results with previous research as well as homogeneous environment. Our findings show that the outcome depends on the type of the environment, and is just the opposite for homogeneous and heterogeneous ones, opposing the existing literature in IPD. Consequently, forgetting and forgiving defectors is the supreme memory management strategy in a competitive, heterogeneous environment. Therefore, forgiveness is an adaptation.