Active set identification and rapid convergence for degenerate primal-dual problems

Fuente: arXiv
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Auteurs principaux: Díaz, Mateo, Lehmann, Pedro Izquierdo, Lu, Haihao, Yang, Jinwen
Format: Preprint
Publié: 2026
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author Díaz, Mateo
Lehmann, Pedro Izquierdo
Lu, Haihao
Yang, Jinwen
author_facet Díaz, Mateo
Lehmann, Pedro Izquierdo
Lu, Haihao
Yang, Jinwen
contents Primal-dual methods for solving convex optimization problems with functional constraints often exhibit a distinct two-stage behavior. Initially, they converge towards a solution at a sublinear rate. Then, after a certain point, the method identifies the set of active constraints and the convergence enters a faster local linear regime. Theory characterizing this phenomenon spans over three decades. However, most existing work only guarantees eventual identification of the active set and relies heavily on nondegeneracy conditions, such as strict complementarity, which often fail to hold in practice. We characterize mild conditions on the problem geometry and the algorithm under which this phenomenon provably occurs. Our guarantees are entirely nonasymptotic and, importantly, do not rely on strict complementarity. Our framework encompasses several widely-used algorithms, including the proximal point method, the primal-dual hybrid gradient method, the alternating direction method of multipliers, and the extragradient method.
format Preprint
id arxiv_https___arxiv_org_abs_2602_10436
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Active set identification and rapid convergence for degenerate primal-dual problems
Díaz, Mateo
Lehmann, Pedro Izquierdo
Lu, Haihao
Yang, Jinwen
Optimization and Control
90C25, 90C06, 90C47, 65K05, 65K10
G.1.6
Primal-dual methods for solving convex optimization problems with functional constraints often exhibit a distinct two-stage behavior. Initially, they converge towards a solution at a sublinear rate. Then, after a certain point, the method identifies the set of active constraints and the convergence enters a faster local linear regime. Theory characterizing this phenomenon spans over three decades. However, most existing work only guarantees eventual identification of the active set and relies heavily on nondegeneracy conditions, such as strict complementarity, which often fail to hold in practice. We characterize mild conditions on the problem geometry and the algorithm under which this phenomenon provably occurs. Our guarantees are entirely nonasymptotic and, importantly, do not rely on strict complementarity. Our framework encompasses several widely-used algorithms, including the proximal point method, the primal-dual hybrid gradient method, the alternating direction method of multipliers, and the extragradient method.
title Active set identification and rapid convergence for degenerate primal-dual problems
topic Optimization and Control
90C25, 90C06, 90C47, 65K05, 65K10
G.1.6
url https://arxiv.org/abs/2602.10436