First-Order Projected Algorithms With the Same Linear Convergence Rate Bounds as Their Unconstrained Counterparts

Fuente: arXiv
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Autori principali: Li, Mengmou, Lestas, Ioannis, Nagahara, Masaaki
Natura: Preprint
Pubblicazione: 2025
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author Li, Mengmou
Lestas, Ioannis
Nagahara, Masaaki
author_facet Li, Mengmou
Lestas, Ioannis
Nagahara, Masaaki
contents In this paper, we propose a systematic approach for extending first-order optimization algorithms, originally designed for unconstrained strongly convex problems, to handle closed and convex set constraints. We show that the resulting projected algorithms retain the same linear convergence rate bounds, provided that the underlying unconstrained optimization algorithms admit a quadratic Lyapunov function obtained from integral quadratic constraint (IQC) analysis. The projected algorithms are constructed by applying a projection in the norm induced by the Lyapunov matrix, ensuring both constraint satisfaction and optimality at the fixed point. Furthermore, under a linear transformation associated with this matrix, the projection becomes non-expansive in the Euclidean norm, allowing the use of the contraction mapping theorem to establish convergence. Our results indicate that, when analyzing worst-case convergence rates or when synthesizing first-order optimization algorithms with potentially higher-order dynamics, it suffices to focus solely on the unconstrained dynamics, since the same parameters or stepsizes can be employed without retuning.
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id arxiv_https___arxiv_org_abs_2503_13965
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle First-Order Projected Algorithms With the Same Linear Convergence Rate Bounds as Their Unconstrained Counterparts
Li, Mengmou
Lestas, Ioannis
Nagahara, Masaaki
Optimization and Control
In this paper, we propose a systematic approach for extending first-order optimization algorithms, originally designed for unconstrained strongly convex problems, to handle closed and convex set constraints. We show that the resulting projected algorithms retain the same linear convergence rate bounds, provided that the underlying unconstrained optimization algorithms admit a quadratic Lyapunov function obtained from integral quadratic constraint (IQC) analysis. The projected algorithms are constructed by applying a projection in the norm induced by the Lyapunov matrix, ensuring both constraint satisfaction and optimality at the fixed point. Furthermore, under a linear transformation associated with this matrix, the projection becomes non-expansive in the Euclidean norm, allowing the use of the contraction mapping theorem to establish convergence. Our results indicate that, when analyzing worst-case convergence rates or when synthesizing first-order optimization algorithms with potentially higher-order dynamics, it suffices to focus solely on the unconstrained dynamics, since the same parameters or stepsizes can be employed without retuning.
title First-Order Projected Algorithms With the Same Linear Convergence Rate Bounds as Their Unconstrained Counterparts
topic Optimization and Control
url https://arxiv.org/abs/2503.13965