Welfare and Fairness in Multi-objective Reinforcement Learning

Fuente: arXiv
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Main Authors: Fan, Zimeng, Peng, Nianli, Tian, Muhang, Fain, Brandon
Format: Preprint
Published: 2022
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author Fan, Zimeng
Peng, Nianli
Tian, Muhang
Fain, Brandon
author_facet Fan, Zimeng
Peng, Nianli
Tian, Muhang
Fain, Brandon
contents We study fair multi-objective reinforcement learning in which an agent must learn a policy that simultaneously achieves high reward on multiple dimensions of a vector-valued reward. Motivated by the fair resource allocation literature, we model this as an expected welfare maximization problem, for some nonlinear fair welfare function of the vector of long-term cumulative rewards. One canonical example of such a function is the Nash Social Welfare, or geometric mean, the log transform of which is also known as the Proportional Fairness objective. We show that even approximately optimal optimization of the expected Nash Social Welfare is computationally intractable even in the tabular case. Nevertheless, we provide a novel adaptation of Q-learning that combines nonlinear scalarized learning updates and non-stationary action selection to learn effective policies for optimizing nonlinear welfare functions. We show that our algorithm is provably convergent, and we demonstrate experimentally that our approach outperforms techniques based on linear scalarization, mixtures of optimal linear scalarizations, or stationary action selection for the Nash Social Welfare Objective.
format Preprint
id arxiv_https___arxiv_org_abs_2212_01382
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Welfare and Fairness in Multi-objective Reinforcement Learning
Fan, Zimeng
Peng, Nianli
Tian, Muhang
Fain, Brandon
Computer Science and Game Theory
Artificial Intelligence
Machine Learning
Multiagent Systems
We study fair multi-objective reinforcement learning in which an agent must learn a policy that simultaneously achieves high reward on multiple dimensions of a vector-valued reward. Motivated by the fair resource allocation literature, we model this as an expected welfare maximization problem, for some nonlinear fair welfare function of the vector of long-term cumulative rewards. One canonical example of such a function is the Nash Social Welfare, or geometric mean, the log transform of which is also known as the Proportional Fairness objective. We show that even approximately optimal optimization of the expected Nash Social Welfare is computationally intractable even in the tabular case. Nevertheless, we provide a novel adaptation of Q-learning that combines nonlinear scalarized learning updates and non-stationary action selection to learn effective policies for optimizing nonlinear welfare functions. We show that our algorithm is provably convergent, and we demonstrate experimentally that our approach outperforms techniques based on linear scalarization, mixtures of optimal linear scalarizations, or stationary action selection for the Nash Social Welfare Objective.
title Welfare and Fairness in Multi-objective Reinforcement Learning
topic Computer Science and Game Theory
Artificial Intelligence
Machine Learning
Multiagent Systems
url https://arxiv.org/abs/2212.01382