Differentially Private Kernelized Contextual Bandits

Fuente: arXiv
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Auteurs principaux: Pavlovic, Nikola, Salgia, Sudeep, Zhao, Qing
Format: Preprint
Publié: 2025
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author Pavlovic, Nikola
Salgia, Sudeep
Zhao, Qing
author_facet Pavlovic, Nikola
Salgia, Sudeep
Zhao, Qing
contents We consider the problem of contextual kernel bandits with stochastic contexts, where the underlying reward function belongs to a known Reproducing Kernel Hilbert Space (RKHS). We study this problem under the additional constraint of joint differential privacy, where the agents needs to ensure that the sequence of query points is differentially private with respect to both the sequence of contexts and rewards. We propose a novel algorithm that improves upon the state of the art and achieves an error rate of $\mathcal{O}\left(\sqrt{\frac{γ_T}{T}} + \frac{γ_T}{T \varepsilon}\right)$ after $T$ queries for a large class of kernel families, where $γ_T$ represents the effective dimensionality of the kernel and $\varepsilon > 0$ is the privacy parameter. Our results are based on a novel estimator for the reward function that simultaneously enjoys high utility along with a low-sensitivity to observed rewards and contexts, which is crucial to obtain an order optimal learning performance with improved dependence on the privacy parameter.
format Preprint
id arxiv_https___arxiv_org_abs_2501_07046
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Differentially Private Kernelized Contextual Bandits
Pavlovic, Nikola
Salgia, Sudeep
Zhao, Qing
Machine Learning
We consider the problem of contextual kernel bandits with stochastic contexts, where the underlying reward function belongs to a known Reproducing Kernel Hilbert Space (RKHS). We study this problem under the additional constraint of joint differential privacy, where the agents needs to ensure that the sequence of query points is differentially private with respect to both the sequence of contexts and rewards. We propose a novel algorithm that improves upon the state of the art and achieves an error rate of $\mathcal{O}\left(\sqrt{\frac{γ_T}{T}} + \frac{γ_T}{T \varepsilon}\right)$ after $T$ queries for a large class of kernel families, where $γ_T$ represents the effective dimensionality of the kernel and $\varepsilon > 0$ is the privacy parameter. Our results are based on a novel estimator for the reward function that simultaneously enjoys high utility along with a low-sensitivity to observed rewards and contexts, which is crucial to obtain an order optimal learning performance with improved dependence on the privacy parameter.
title Differentially Private Kernelized Contextual Bandits
topic Machine Learning
url https://arxiv.org/abs/2501.07046