Choosing Public Datasets for Private Machine Learning via Gradient Subspace Distance

Fuente: arXiv
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Main Authors: Gu, Xin, Kamath, Gautam, Wu, Zhiwei Steven
Format: Preprint
Published: 2023
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author Gu, Xin
Kamath, Gautam
Wu, Zhiwei Steven
author_facet Gu, Xin
Kamath, Gautam
Wu, Zhiwei Steven
contents Differentially private stochastic gradient descent privatizes model training by injecting noise into each iteration, where the noise magnitude increases with the number of model parameters. Recent works suggest that we can reduce the noise by leveraging public data for private machine learning, by projecting gradients onto a subspace prescribed by the public data. However, given a choice of public datasets, it is not a priori clear which one may be most appropriate for the private task. We give an algorithm for selecting a public dataset by measuring a low-dimensional subspace distance between gradients of the public and private examples. We provide theoretical analysis demonstrating that the excess risk scales with this subspace distance. This distance is easy to compute and robust to modifications in the setting. Empirical evaluation shows that trained model accuracy is monotone in this distance.
format Preprint
id arxiv_https___arxiv_org_abs_2303_01256
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Choosing Public Datasets for Private Machine Learning via Gradient Subspace Distance
Gu, Xin
Kamath, Gautam
Wu, Zhiwei Steven
Machine Learning
Cryptography and Security
Computer Vision and Pattern Recognition
Data Structures and Algorithms
Differentially private stochastic gradient descent privatizes model training by injecting noise into each iteration, where the noise magnitude increases with the number of model parameters. Recent works suggest that we can reduce the noise by leveraging public data for private machine learning, by projecting gradients onto a subspace prescribed by the public data. However, given a choice of public datasets, it is not a priori clear which one may be most appropriate for the private task. We give an algorithm for selecting a public dataset by measuring a low-dimensional subspace distance between gradients of the public and private examples. We provide theoretical analysis demonstrating that the excess risk scales with this subspace distance. This distance is easy to compute and robust to modifications in the setting. Empirical evaluation shows that trained model accuracy is monotone in this distance.
title Choosing Public Datasets for Private Machine Learning via Gradient Subspace Distance
topic Machine Learning
Cryptography and Security
Computer Vision and Pattern Recognition
Data Structures and Algorithms
url https://arxiv.org/abs/2303.01256