Overcoming unfairness via repeated interactions in mini-ultimatum game

Fuente: arXiv
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Main Authors: Mandal, Prosanta, Patra, Arunava, Chakraborty, Sagar
Format: Preprint
Published: 2026
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author Mandal, Prosanta
Patra, Arunava
Chakraborty, Sagar
author_facet Mandal, Prosanta
Patra, Arunava
Chakraborty, Sagar
contents Repeated interactions are ubiquitous and known to promote social behaviour. While research often focuses on cooperation in the Prisoner's Dilemma, experimental evidence suggests repeated interactions also foster fairness. This study addresses a gap in the literature by theoretically modelling the evolution of fairness within a repeated mini-ultimatum game. Specifically, we construct a repeated-game framework where offerers and accepters interact using reactive strategies. We then investigate whether fair reactive strategy pairs are resilient against unfair mutants in a two-species population. By analyzing short-term evolutionary stability via the concept of two-species evolutionary stable strategy, we identify a critical effective game length: below this value, fairness is promoted by offerers and accepters who comply with their partner's past actions. Above this critical value, fairness is maintained by `complier' offerers and fair accepters. We also show that specific reactive strategies effectively facilitate the emergence and sustenance of fairness in long-term mutation-selection dynamics. To this end, we develop a two-population stochastic dynamics model -- a generalization of classical adaptive dynamics -- that accounts for finite population sizes and non-local mutants in the reactive strategy space.
format Preprint
id arxiv_https___arxiv_org_abs_2604_03625
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Overcoming unfairness via repeated interactions in mini-ultimatum game
Mandal, Prosanta
Patra, Arunava
Chakraborty, Sagar
Adaptation and Self-Organizing Systems
Theoretical Economics
Biological Physics
Populations and Evolution
Repeated interactions are ubiquitous and known to promote social behaviour. While research often focuses on cooperation in the Prisoner's Dilemma, experimental evidence suggests repeated interactions also foster fairness. This study addresses a gap in the literature by theoretically modelling the evolution of fairness within a repeated mini-ultimatum game. Specifically, we construct a repeated-game framework where offerers and accepters interact using reactive strategies. We then investigate whether fair reactive strategy pairs are resilient against unfair mutants in a two-species population. By analyzing short-term evolutionary stability via the concept of two-species evolutionary stable strategy, we identify a critical effective game length: below this value, fairness is promoted by offerers and accepters who comply with their partner's past actions. Above this critical value, fairness is maintained by `complier' offerers and fair accepters. We also show that specific reactive strategies effectively facilitate the emergence and sustenance of fairness in long-term mutation-selection dynamics. To this end, we develop a two-population stochastic dynamics model -- a generalization of classical adaptive dynamics -- that accounts for finite population sizes and non-local mutants in the reactive strategy space.
title Overcoming unfairness via repeated interactions in mini-ultimatum game
topic Adaptation and Self-Organizing Systems
Theoretical Economics
Biological Physics
Populations and Evolution
url https://arxiv.org/abs/2604.03625