Multi-objective Reinforcement Learning With Augmented States Requires Rewards After Deployment

Fuente: arXiv
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Main Authors: Vamplew, Peter, Foale, Cameron
Format: Preprint
Published: 2026
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author Vamplew, Peter
Foale, Cameron
author_facet Vamplew, Peter
Foale, Cameron
contents This research note identifies a previously overlooked distinction between multi-objective reinforcement learning (MORL), and more conventional single-objective reinforcement learning (RL). It has previously been noted that the optimal policy for an MORL agent with a non-linear utility function is required to be conditioned on both the current environmental state and on some measure of the previously accrued reward. This is generally implemented by concatenating the observed state of the environment with the discounted sum of previous rewards to create an augmented state. While augmented states have been widely-used in the MORL literature, one implication of their use has not previously been reported -- namely that they require the agent to have continued access to the reward signal (or a proxy thereof) after deployment, even if no further learning is required. This note explains why this is the case, and considers the practical repercussions of this requirement.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15757
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Multi-objective Reinforcement Learning With Augmented States Requires Rewards After Deployment
Vamplew, Peter
Foale, Cameron
Machine Learning
This research note identifies a previously overlooked distinction between multi-objective reinforcement learning (MORL), and more conventional single-objective reinforcement learning (RL). It has previously been noted that the optimal policy for an MORL agent with a non-linear utility function is required to be conditioned on both the current environmental state and on some measure of the previously accrued reward. This is generally implemented by concatenating the observed state of the environment with the discounted sum of previous rewards to create an augmented state. While augmented states have been widely-used in the MORL literature, one implication of their use has not previously been reported -- namely that they require the agent to have continued access to the reward signal (or a proxy thereof) after deployment, even if no further learning is required. This note explains why this is the case, and considers the practical repercussions of this requirement.
title Multi-objective Reinforcement Learning With Augmented States Requires Rewards After Deployment
topic Machine Learning
url https://arxiv.org/abs/2604.15757