Complexity of Linearized Perturbed Augmented Lagrangian Methods for Nonsmooth Nonconvex Optimization with Nonlinear Equality Constraints

Fuente: arXiv
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Autori principali: Bourkhissi, Lahcen El, Necoara, Ion, Patrinos, Panagiotis, Tran-Dinh, Quoc
Natura: Preprint
Pubblicazione: 2025
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author Bourkhissi, Lahcen El
Necoara, Ion
Patrinos, Panagiotis
Tran-Dinh, Quoc
author_facet Bourkhissi, Lahcen El
Necoara, Ion
Patrinos, Panagiotis
Tran-Dinh, Quoc
contents This paper addresses a class of general nonsmooth and nonconvex composite optimization problems subject to nonlinear equality constraints. We assume that a part of the objective function and the functional constraints exhibit local smoothness. To tackle this challenging class of problems, we propose a novel linearized perturbed augmented Lagrangian method. This method incorporates a perturbation in the augmented Lagrangian function by scaling the dual variable with a sub-unitary parameter. Furthermore, we linearize the smooth components of the objective and the constraints within the perturbed Lagrangian function at the current iterate, while preserving the nonsmooth components. This approach, inspired by prox-linear (or Gauss-Newton) methods, results in a convex subproblem that is typically easy to solve. The solution of this subproblem then serves as the next primal iterate, followed by a perturbed ascent step to update the dual variables. Under a newly introduced constraint qualification condition, we establish the boundedness of the dual iterates. We derive convergence guarantees for the primal iterates, proving convergence to an $ε$-first-order optimal solution within $\mathcal{O}(ε^{-3})$ evaluations of the problem's functions and their first derivatives. Moreover, when the problem exhibits for example a semialgebraic property, we derive improved local convergence results. Finally, we validate the theoretical findings and assess the practical performance of our proposed algorithm through numerical comparisons with existing state-of-the-art methods.
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publishDate 2025
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spellingShingle Complexity of Linearized Perturbed Augmented Lagrangian Methods for Nonsmooth Nonconvex Optimization with Nonlinear Equality Constraints
Bourkhissi, Lahcen El
Necoara, Ion
Patrinos, Panagiotis
Tran-Dinh, Quoc
Optimization and Control
This paper addresses a class of general nonsmooth and nonconvex composite optimization problems subject to nonlinear equality constraints. We assume that a part of the objective function and the functional constraints exhibit local smoothness. To tackle this challenging class of problems, we propose a novel linearized perturbed augmented Lagrangian method. This method incorporates a perturbation in the augmented Lagrangian function by scaling the dual variable with a sub-unitary parameter. Furthermore, we linearize the smooth components of the objective and the constraints within the perturbed Lagrangian function at the current iterate, while preserving the nonsmooth components. This approach, inspired by prox-linear (or Gauss-Newton) methods, results in a convex subproblem that is typically easy to solve. The solution of this subproblem then serves as the next primal iterate, followed by a perturbed ascent step to update the dual variables. Under a newly introduced constraint qualification condition, we establish the boundedness of the dual iterates. We derive convergence guarantees for the primal iterates, proving convergence to an $ε$-first-order optimal solution within $\mathcal{O}(ε^{-3})$ evaluations of the problem's functions and their first derivatives. Moreover, when the problem exhibits for example a semialgebraic property, we derive improved local convergence results. Finally, we validate the theoretical findings and assess the practical performance of our proposed algorithm through numerical comparisons with existing state-of-the-art methods.
title Complexity of Linearized Perturbed Augmented Lagrangian Methods for Nonsmooth Nonconvex Optimization with Nonlinear Equality Constraints
topic Optimization and Control
url https://arxiv.org/abs/2503.01056