Long-Horizon Model-Based Offline Reinforcement Learning Without Explicit Conservatism

Fuente: arXiv
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Hauptverfasser: Ni, Tianwei, Derman, Esther, Jain, Vineet, Taboga, Vincent, Ravanbakhsh, Siamak, Bacon, Pierre-Luc
Format: Preprint
Veröffentlicht: 2025
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author Ni, Tianwei
Derman, Esther
Jain, Vineet
Taboga, Vincent
Ravanbakhsh, Siamak
Bacon, Pierre-Luc
author_facet Ni, Tianwei
Derman, Esther
Jain, Vineet
Taboga, Vincent
Ravanbakhsh, Siamak
Bacon, Pierre-Luc
contents Popular offline reinforcement learning (RL) methods rely on explicit conservatism, penalizing out-of-dataset actions or restricting rollout horizons. We question the universality of this principle and revisit a complementary Bayesian perspective for test-time adaptation. By modeling a posterior over world models and training a history-dependent agent to maximize expected return, the Bayesian approach directly addresses epistemic uncertainty without explicit conservatism. We first illustrate in a bandit setting that Bayesianism excels on low-quality datasets where conservatism fails. Scaling to realistic tasks, we find that long-horizon rollouts are essential to control value overestimation once conservatism is removed. We introduce design choices that enable learning from long-horizon rollouts while mitigating compounding model errors, yielding our algorithm, NEUBAY, grounded in the neutral Bayesian principle. On D4RL and NeoRL benchmarks, NEUBAY is competitive with leading conservative algorithms, achieving new state-of-the-art on 7 datasets with rollout horizons of several hundred steps. Finally, we characterize datasets by quality and coverage to identify when NEUBAY is preferable to conservative methods.
format Preprint
id arxiv_https___arxiv_org_abs_2512_04341
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Long-Horizon Model-Based Offline Reinforcement Learning Without Explicit Conservatism
Ni, Tianwei
Derman, Esther
Jain, Vineet
Taboga, Vincent
Ravanbakhsh, Siamak
Bacon, Pierre-Luc
Machine Learning
Popular offline reinforcement learning (RL) methods rely on explicit conservatism, penalizing out-of-dataset actions or restricting rollout horizons. We question the universality of this principle and revisit a complementary Bayesian perspective for test-time adaptation. By modeling a posterior over world models and training a history-dependent agent to maximize expected return, the Bayesian approach directly addresses epistemic uncertainty without explicit conservatism. We first illustrate in a bandit setting that Bayesianism excels on low-quality datasets where conservatism fails. Scaling to realistic tasks, we find that long-horizon rollouts are essential to control value overestimation once conservatism is removed. We introduce design choices that enable learning from long-horizon rollouts while mitigating compounding model errors, yielding our algorithm, NEUBAY, grounded in the neutral Bayesian principle. On D4RL and NeoRL benchmarks, NEUBAY is competitive with leading conservative algorithms, achieving new state-of-the-art on 7 datasets with rollout horizons of several hundred steps. Finally, we characterize datasets by quality and coverage to identify when NEUBAY is preferable to conservative methods.
title Long-Horizon Model-Based Offline Reinforcement Learning Without Explicit Conservatism
topic Machine Learning
url https://arxiv.org/abs/2512.04341