RIE-Greedy: Regularization-Induced Exploration for Contextual Bandits

Fuente: arXiv
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Hauptverfasser: Li, Tong, Casanova, Thiago de Queiroz, Schwartz, Eric M., Kostyuk, Victor, Kong, Dehan, Williams, Joseph J.
Format: Preprint
Veröffentlicht: 2026
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author Li, Tong
Casanova, Thiago de Queiroz
Schwartz, Eric M.
Kostyuk, Victor
Kong, Dehan
Williams, Joseph J.
author_facet Li, Tong
Casanova, Thiago de Queiroz
Schwartz, Eric M.
Kostyuk, Victor
Kong, Dehan
Williams, Joseph J.
contents Real-world contextual bandit problems with complex reward models are often tackled with iteratively trained models, such as boosting trees. However, it is difficult to directly apply simple and effective exploration strategies--such as Thompson Sampling or UCB--on top of those black-box estimators. Existing approaches rely on sophisticated assumptions or intractable procedures that are hard to verify and implement in practice. In this work, we explore the use of an exploration-free (pure-greedy) action selection strategy, that exploits the randomness inherent in model fitting process as an intrinsic source of exploration. More specifically, we note that the stochasticity in cross-validation based regularization process can naturally induce Thompson Sampling-like exploration. We show that this regularization-induced exploration is theoretically equivalent to Thompson Sampling in the two-armed bandit case and empirically leads to reliable exploration in large-scale business environments compared to benchmark methods such as epsilon-greedy and other state-of-the-art approaches. Overall, our work reveals how regularized estimator training itself can induce effective exploration, offering both theoretical insight and practical guidance for contextual bandit design.
format Preprint
id arxiv_https___arxiv_org_abs_2603_11276
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle RIE-Greedy: Regularization-Induced Exploration for Contextual Bandits
Li, Tong
Casanova, Thiago de Queiroz
Schwartz, Eric M.
Kostyuk, Victor
Kong, Dehan
Williams, Joseph J.
Machine Learning
Real-world contextual bandit problems with complex reward models are often tackled with iteratively trained models, such as boosting trees. However, it is difficult to directly apply simple and effective exploration strategies--such as Thompson Sampling or UCB--on top of those black-box estimators. Existing approaches rely on sophisticated assumptions or intractable procedures that are hard to verify and implement in practice. In this work, we explore the use of an exploration-free (pure-greedy) action selection strategy, that exploits the randomness inherent in model fitting process as an intrinsic source of exploration. More specifically, we note that the stochasticity in cross-validation based regularization process can naturally induce Thompson Sampling-like exploration. We show that this regularization-induced exploration is theoretically equivalent to Thompson Sampling in the two-armed bandit case and empirically leads to reliable exploration in large-scale business environments compared to benchmark methods such as epsilon-greedy and other state-of-the-art approaches. Overall, our work reveals how regularized estimator training itself can induce effective exploration, offering both theoretical insight and practical guidance for contextual bandit design.
title RIE-Greedy: Regularization-Induced Exploration for Contextual Bandits
topic Machine Learning
url https://arxiv.org/abs/2603.11276