Tannenbaum's gain-margin optimization meets Polyak's heavy-ball algorithm

Fuente: arXiv
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Autores principales: Wu, Wuwei, Chen, Jie, Jovanović, Mihailo R., Georgiou, Tryphon T.
Formato: Preprint
Publicado: 2024
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author Wu, Wuwei
Chen, Jie
Jovanović, Mihailo R.
Georgiou, Tryphon T.
author_facet Wu, Wuwei
Chen, Jie
Jovanović, Mihailo R.
Georgiou, Tryphon T.
contents This paper highlights an apparent, yet relatively unknown link between algorithm design in optimization theory and controller synthesis in robust control. Specifically, quadratic optimization can be recast as a regulation problem within the framework of $\mathcal{H}_\infty$ control. From this vantage point, the optimality of Polyak's fastest heavy-ball algorithm can be ascertained as a solution to a gain margin optimization problem. The approach is independent of Polyak's original and brilliant argument, and relies on foundational work by Tannenbaum, who introduced and solved gain margin optimization via Nevanlinna--Pick interpolation theory. The link between first-order optimization methods and robust control sheds new light on the limits of algorithmic performance of such methods, and suggests a framework where similar computational tasks can be systematically studied and algorithms optimized. In particular, it raises the question as to whether periodically scheduled algorithms can achieve faster rates for quadratic optimization, in a manner analogous to periodic control that extends the gain margin beyond that of time-invariant control. This turns out not to be the case, due to the analytic obstruction of a transmission zero that is inherent in causal schemes. Interestingly, this obstruction can be removed with implicit algorithms, cast as feedback regulation problems with causal, but not strictly causal dynamics, thereby devoid of the transmission zero at infinity and able to achieve superior convergence rates.
format Preprint
id arxiv_https___arxiv_org_abs_2409_19882
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tannenbaum's gain-margin optimization meets Polyak's heavy-ball algorithm
Wu, Wuwei
Chen, Jie
Jovanović, Mihailo R.
Georgiou, Tryphon T.
Systems and Control
Numerical Analysis
Optimization and Control
93B36, 93B52, 65-XX, 49Mxx, 49M15, 30E05
This paper highlights an apparent, yet relatively unknown link between algorithm design in optimization theory and controller synthesis in robust control. Specifically, quadratic optimization can be recast as a regulation problem within the framework of $\mathcal{H}_\infty$ control. From this vantage point, the optimality of Polyak's fastest heavy-ball algorithm can be ascertained as a solution to a gain margin optimization problem. The approach is independent of Polyak's original and brilliant argument, and relies on foundational work by Tannenbaum, who introduced and solved gain margin optimization via Nevanlinna--Pick interpolation theory. The link between first-order optimization methods and robust control sheds new light on the limits of algorithmic performance of such methods, and suggests a framework where similar computational tasks can be systematically studied and algorithms optimized. In particular, it raises the question as to whether periodically scheduled algorithms can achieve faster rates for quadratic optimization, in a manner analogous to periodic control that extends the gain margin beyond that of time-invariant control. This turns out not to be the case, due to the analytic obstruction of a transmission zero that is inherent in causal schemes. Interestingly, this obstruction can be removed with implicit algorithms, cast as feedback regulation problems with causal, but not strictly causal dynamics, thereby devoid of the transmission zero at infinity and able to achieve superior convergence rates.
title Tannenbaum's gain-margin optimization meets Polyak's heavy-ball algorithm
topic Systems and Control
Numerical Analysis
Optimization and Control
93B36, 93B52, 65-XX, 49Mxx, 49M15, 30E05
url https://arxiv.org/abs/2409.19882