Remarks on the Polyak-Lojasiewicz inequality and the convergence of gradient systems

Fuente: arXiv
Guardado en:
Detalles Bibliográficos
Autores principales: de Oliveira, Arthur Castello B., Cui, Leilei, Sontag, Eduardo D.
Formato: Preprint
Publicado: 2025
Materias:
Acceso en línea:
Etiquetas: Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
_version_ 1866915218913755136
author de Oliveira, Arthur Castello B.
Cui, Leilei
Sontag, Eduardo D.
author_facet de Oliveira, Arthur Castello B.
Cui, Leilei
Sontag, Eduardo D.
contents This work explores generalizations of the Polyak-Lojasiewicz inequality (PLI) and their implications for the convergence behavior of gradient flows in optimization problems. Motivated by the continuous-time linear quadratic regulator (CT-LQR) policy optimization problem -- where only a weaker version of the PLI is characterized in the literature -- this work shows that while weaker conditions are sufficient for global convergence to, and optimality of the set of critical points of the cost function, the "profile" of the gradient flow solution can change significantly depending on which "flavor" of inequality the cost satisfies. After a general theoretical analysis, we focus on fitting the CT-LQR policy optimization problem to the proposed framework, showing that, in fact, it can never satisfy a PLI in its strongest form. We follow up our analysis with a brief discussion on the difference between continuous- and discrete-time LQR policy optimization, and end the paper with some intuition on the extension of this framework to optimization problems with L1 regularization and solved through proximal gradient flows.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23641
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Remarks on the Polyak-Lojasiewicz inequality and the convergence of gradient systems
de Oliveira, Arthur Castello B.
Cui, Leilei
Sontag, Eduardo D.
Optimization and Control
Artificial Intelligence
Systems and Control
This work explores generalizations of the Polyak-Lojasiewicz inequality (PLI) and their implications for the convergence behavior of gradient flows in optimization problems. Motivated by the continuous-time linear quadratic regulator (CT-LQR) policy optimization problem -- where only a weaker version of the PLI is characterized in the literature -- this work shows that while weaker conditions are sufficient for global convergence to, and optimality of the set of critical points of the cost function, the "profile" of the gradient flow solution can change significantly depending on which "flavor" of inequality the cost satisfies. After a general theoretical analysis, we focus on fitting the CT-LQR policy optimization problem to the proposed framework, showing that, in fact, it can never satisfy a PLI in its strongest form. We follow up our analysis with a brief discussion on the difference between continuous- and discrete-time LQR policy optimization, and end the paper with some intuition on the extension of this framework to optimization problems with L1 regularization and solved through proximal gradient flows.
title Remarks on the Polyak-Lojasiewicz inequality and the convergence of gradient systems
topic Optimization and Control
Artificial Intelligence
Systems and Control
url https://arxiv.org/abs/2503.23641