Fairness of Exposure in Online Restless Multi-armed Bandits

Fuente: arXiv
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Main Authors: Sood, Archit, Jain, Shweta, Gujar, Sujit
Format: Preprint
Published: 2024
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author Sood, Archit
Jain, Shweta
Gujar, Sujit
author_facet Sood, Archit
Jain, Shweta
Gujar, Sujit
contents Restless multi-armed bandits (RMABs) generalize the multi-armed bandits where each arm exhibits Markovian behavior and transitions according to their transition dynamics. Solutions to RMAB exist for both offline and online cases. However, they do not consider the distribution of pulls among the arms. Studies have shown that optimal policies lead to unfairness, where some arms are not exposed enough. Existing works in fairness in RMABs focus heavily on the offline case, which diminishes their application in real-world scenarios where the environment is largely unknown. In the online scenario, we propose the first fair RMAB framework, where each arm receives pulls in proportion to its merit. We define the merit of an arm as a function of its stationary reward distribution. We prove that our algorithm achieves sublinear fairness regret in the single pull case $O(\sqrt{T\ln T})$, with $T$ being the total number of episodes. Empirically, we show that our algorithm performs well in the multi-pull scenario as well.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06348
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fairness of Exposure in Online Restless Multi-armed Bandits
Sood, Archit
Jain, Shweta
Gujar, Sujit
Machine Learning
Restless multi-armed bandits (RMABs) generalize the multi-armed bandits where each arm exhibits Markovian behavior and transitions according to their transition dynamics. Solutions to RMAB exist for both offline and online cases. However, they do not consider the distribution of pulls among the arms. Studies have shown that optimal policies lead to unfairness, where some arms are not exposed enough. Existing works in fairness in RMABs focus heavily on the offline case, which diminishes their application in real-world scenarios where the environment is largely unknown. In the online scenario, we propose the first fair RMAB framework, where each arm receives pulls in proportion to its merit. We define the merit of an arm as a function of its stationary reward distribution. We prove that our algorithm achieves sublinear fairness regret in the single pull case $O(\sqrt{T\ln T})$, with $T$ being the total number of episodes. Empirically, we show that our algorithm performs well in the multi-pull scenario as well.
title Fairness of Exposure in Online Restless Multi-armed Bandits
topic Machine Learning
url https://arxiv.org/abs/2402.06348