Adaptive Riemannian ADMM for Nonsmooth Optimization: Optimal Complexity without Smoothing

Fuente: arXiv
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Main Authors: Deng, Kangkang, Jin, Jiachen, Hu, Jiang, Wang, Hongxia
Format: Preprint
Published: 2025
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author Deng, Kangkang
Jin, Jiachen
Hu, Jiang
Wang, Hongxia
author_facet Deng, Kangkang
Jin, Jiachen
Hu, Jiang
Wang, Hongxia
contents We study the problem of minimizing the sum of a smooth function and a nonsmooth convex regularizer over a compact Riemannian submanifold embedded in Euclidean space. By introducing an auxiliary splitting variable, we propose an adaptive Riemannian alternating direction method of multipliers (ARADMM), which, for the first time, achieves convergence without requiring smoothing of the nonsmooth term. Our approach involves only one Riemannian gradient evaluation and one proximal update per iteration. Through careful and adaptive coordination of the stepsizes and penalty parameters, we establish an optimal iteration complexity of order $\mathcal{O}(ε^{-3})$ for finding an $ε$-approximate KKT point, matching the complexity of existing smoothing technique-based Riemannian ADMM methods. Extensive numerical experiments on sparse PCA and robust subspace recovery demonstrate that our ARADMM consistently outperforms state-of-the-art Riemannian ADMM variants in convergence speed and solution quality.
format Preprint
id arxiv_https___arxiv_org_abs_2510_18617
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Adaptive Riemannian ADMM for Nonsmooth Optimization: Optimal Complexity without Smoothing
Deng, Kangkang
Jin, Jiachen
Hu, Jiang
Wang, Hongxia
Optimization and Control
We study the problem of minimizing the sum of a smooth function and a nonsmooth convex regularizer over a compact Riemannian submanifold embedded in Euclidean space. By introducing an auxiliary splitting variable, we propose an adaptive Riemannian alternating direction method of multipliers (ARADMM), which, for the first time, achieves convergence without requiring smoothing of the nonsmooth term. Our approach involves only one Riemannian gradient evaluation and one proximal update per iteration. Through careful and adaptive coordination of the stepsizes and penalty parameters, we establish an optimal iteration complexity of order $\mathcal{O}(ε^{-3})$ for finding an $ε$-approximate KKT point, matching the complexity of existing smoothing technique-based Riemannian ADMM methods. Extensive numerical experiments on sparse PCA and robust subspace recovery demonstrate that our ARADMM consistently outperforms state-of-the-art Riemannian ADMM variants in convergence speed and solution quality.
title Adaptive Riemannian ADMM for Nonsmooth Optimization: Optimal Complexity without Smoothing
topic Optimization and Control
url https://arxiv.org/abs/2510.18617