A Trust-Region Method for Nonsmooth Nonconvex Optimization

A Trust-Region Method for Nonsmooth Nonconvex Optimization

Year:    2023

Author:    Ziang Chen, Andre Milzarek, Zaiwen Wen

Journal of Computational Mathematics, Vol. 41 (2023), Iss. 4 : pp. 683–716

Abstract

We propose a trust-region type method for a class of nonsmooth nonconvex optimization problems where the objective function is a summation of a (probably nonconvex) smooth function and a (probably nonsmooth) convex function. The model function of our trust-region subproblem is always quadratic and the linear term of the model is generated using abstract descent directions. Therefore, the trust-region subproblems can be easily constructed as well as efficiently solved by cheap and standard methods. When the accuracy of the model function at the solution of the subproblem is not sufficient, we add a safeguard on the stepsizes for improving the accuracy. For a class of functions that can be "truncated'', an additional truncation step is defined and a stepsize modification strategy is designed. The overall scheme converges globally and we establish fast local convergence under suitable assumptions. In particular, using a connection with a smooth Riemannian trust-region method, we prove local quadratic convergence for partly smooth functions under a strict complementary condition. Preliminary numerical results on a family of $\ell_1$-optimization problems are reported and demonstrate the efficiency of our approach.

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Journal Article Details

Publisher Name:    Global Science Press

Language:    English

DOI:    https://doi.org/10.4208/jcm.2110-m2020-0317

Journal of Computational Mathematics, Vol. 41 (2023), Iss. 4 : pp. 683–716

Published online:    2023-01

AMS Subject Headings:   

Copyright:    COPYRIGHT: © Global Science Press

Pages:    34

Keywords:    Trust-region method Nonsmooth composite programs Quadratic model function Global and local convergence.

Author Details

Ziang Chen

Andre Milzarek

Zaiwen Wen

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    https://doi.org/10.1007/s10898-023-01326-4 [Citations: 0]