Sample Complexity of Preference-Based Nonparametric Off-Policy Evaluation with Deep Networks

Fuente: arXiv
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Main Authors: Li, Zihao, Ji, Xiang, Chen, Minshuo, Wang, Mengdi
Format: Preprint
Published: 2023
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author Li, Zihao
Ji, Xiang
Chen, Minshuo
Wang, Mengdi
author_facet Li, Zihao
Ji, Xiang
Chen, Minshuo
Wang, Mengdi
contents A recently popular approach to solving reinforcement learning is with data from human preferences. In fact, human preference data are now used with classic reinforcement learning algorithms such as actor-critic methods, which involve evaluating an intermediate policy over a reward learned from human preference data with distribution shift, known as off-policy evaluation (OPE). Such algorithm includes (i) learning reward function from human preference dataset, and (ii) learning expected cumulative reward of a target policy. Despite the huge empirical success, existing OPE methods with preference data often lack theoretical understanding and rely heavily on heuristics. In this paper, we study the sample efficiency of OPE with human preference and establish a statistical guarantee for it. Specifically, we approach OPE by learning the value function by fitted-Q-evaluation with a deep neural network. By appropriately selecting the size of a ReLU network, we show that one can leverage any low-dimensional manifold structure in the Markov decision process and obtain a sample-efficient estimator without suffering from the curse of high data ambient dimensionality. Under the assumption of high reward smoothness, our results \textit{almost align with the classical OPE results with observable reward data}. To the best of our knowledge, this is the first result that establishes a \textit{provably efficient} guarantee for off-policy evaluation with RLHF.
format Preprint
id arxiv_https___arxiv_org_abs_2310_10556
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Sample Complexity of Preference-Based Nonparametric Off-Policy Evaluation with Deep Networks
Li, Zihao
Ji, Xiang
Chen, Minshuo
Wang, Mengdi
Machine Learning
A recently popular approach to solving reinforcement learning is with data from human preferences. In fact, human preference data are now used with classic reinforcement learning algorithms such as actor-critic methods, which involve evaluating an intermediate policy over a reward learned from human preference data with distribution shift, known as off-policy evaluation (OPE). Such algorithm includes (i) learning reward function from human preference dataset, and (ii) learning expected cumulative reward of a target policy. Despite the huge empirical success, existing OPE methods with preference data often lack theoretical understanding and rely heavily on heuristics. In this paper, we study the sample efficiency of OPE with human preference and establish a statistical guarantee for it. Specifically, we approach OPE by learning the value function by fitted-Q-evaluation with a deep neural network. By appropriately selecting the size of a ReLU network, we show that one can leverage any low-dimensional manifold structure in the Markov decision process and obtain a sample-efficient estimator without suffering from the curse of high data ambient dimensionality. Under the assumption of high reward smoothness, our results \textit{almost align with the classical OPE results with observable reward data}. To the best of our knowledge, this is the first result that establishes a \textit{provably efficient} guarantee for off-policy evaluation with RLHF.
title Sample Complexity of Preference-Based Nonparametric Off-Policy Evaluation with Deep Networks
topic Machine Learning
url https://arxiv.org/abs/2310.10556