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Main Authors: Loh, Wei Min, Sinha, Sajib Kumer, Agarwal, Ankur, Poupart, Pascal
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2603.16755
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author Loh, Wei Min
Sinha, Sajib Kumer
Agarwal, Ankur
Poupart, Pascal
author_facet Loh, Wei Min
Sinha, Sajib Kumer
Agarwal, Ankur
Poupart, Pascal
contents Contextual bandits are incredibly useful in many practical problems. We go one step further by devising a more realistic problem that combines: (1) contextual bandits with dense arm features, (2) non-linear reward functions, and (3) a generalization of correlated bandits where reward distributions change over time but the degree of correlation maintains. This formulation lends itself to a wider set of applications such as recommendation tasks. To solve this problem, we introduce conditionally coupled contextual C3 Thompson sampling for Bernoulli bandits. It combines an improved Nadaraya-Watson estimator on an embedding space with Thompson sampling that allows online learning without retraining. Empirical results show that C3 outperforms the next best algorithm by 5.7% lower average cumulative regret on four OpenML tabular datasets as well as demonstrating a 12.4% click lift on Microsoft News Dataset (MIND) compared to other algorithms.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16755
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Practical Algorithm for Feature-Rich, Non-Stationary Bandit Problems
Loh, Wei Min
Sinha, Sajib Kumer
Agarwal, Ankur
Poupart, Pascal
Machine Learning
Contextual bandits are incredibly useful in many practical problems. We go one step further by devising a more realistic problem that combines: (1) contextual bandits with dense arm features, (2) non-linear reward functions, and (3) a generalization of correlated bandits where reward distributions change over time but the degree of correlation maintains. This formulation lends itself to a wider set of applications such as recommendation tasks. To solve this problem, we introduce conditionally coupled contextual C3 Thompson sampling for Bernoulli bandits. It combines an improved Nadaraya-Watson estimator on an embedding space with Thompson sampling that allows online learning without retraining. Empirical results show that C3 outperforms the next best algorithm by 5.7% lower average cumulative regret on four OpenML tabular datasets as well as demonstrating a 12.4% click lift on Microsoft News Dataset (MIND) compared to other algorithms.
title A Practical Algorithm for Feature-Rich, Non-Stationary Bandit Problems
topic Machine Learning
url https://arxiv.org/abs/2603.16755