On the B-subdifferential of proximal operators of affine-constrained $\ell_1$ regularizer

Fuente: arXiv
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Main Authors: Li, Xudong, Lin, Meixia, Toh, Kim-Chuan
Format: Preprint
Published: 2025
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author Li, Xudong
Lin, Meixia
Toh, Kim-Chuan
author_facet Li, Xudong
Lin, Meixia
Toh, Kim-Chuan
contents In this work, we study the affine-constrained $\ell_1$ regularizers, which frequently arise in statistical and machine learning problems across a variety of applications, including microbiome compositional data analysis and sparse subspace clustering. With the aim of developing scalable second-order methods for solving optimization problems involving such regularizers, we analyze the associated proximal mapping and characterize its generalized differentiability, with a focus on its B-subdifferential. The revealed structured sparsity in the B-subdifferential enables us to design efficient algorithms within the proximal point framework. Extensive numerical experiments on real applications, including comparisons with state-of-the-art solvers, further demonstrate the superior performance of our approach. Our findings provide new insights into the sensitivity and stability properties of affine-constrained nonsmooth regularizers, and contribute to the development of fast second-order methods for a class of structured, constrained sparse learning problems.
format Preprint
id arxiv_https___arxiv_org_abs_2510_06642
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the B-subdifferential of proximal operators of affine-constrained $\ell_1$ regularizer
Li, Xudong
Lin, Meixia
Toh, Kim-Chuan
Optimization and Control
In this work, we study the affine-constrained $\ell_1$ regularizers, which frequently arise in statistical and machine learning problems across a variety of applications, including microbiome compositional data analysis and sparse subspace clustering. With the aim of developing scalable second-order methods for solving optimization problems involving such regularizers, we analyze the associated proximal mapping and characterize its generalized differentiability, with a focus on its B-subdifferential. The revealed structured sparsity in the B-subdifferential enables us to design efficient algorithms within the proximal point framework. Extensive numerical experiments on real applications, including comparisons with state-of-the-art solvers, further demonstrate the superior performance of our approach. Our findings provide new insights into the sensitivity and stability properties of affine-constrained nonsmooth regularizers, and contribute to the development of fast second-order methods for a class of structured, constrained sparse learning problems.
title On the B-subdifferential of proximal operators of affine-constrained $\ell_1$ regularizer
topic Optimization and Control
url https://arxiv.org/abs/2510.06642