{"title":"Distributed inexact Newton method with adaptive step sizes.","authors":"Dušan Jakovetić, Nataša Krejić, Greta Malaspina","doi":"10.1007/s10589-025-00666-z","DOIUrl":"10.1007/s10589-025-00666-z","url":null,"abstract":"<p><p>We consider two formulations for distributed optimization wherein <i>N</i> nodes in a generic connected network solve a problem of common interest: distributed personalized optimization and consensus optimization. A new method termed DINAS (Distributed Inexact Newton method with Adaptive step size) is proposed. DINAS employs large adaptively computed step sizes, requires a reduced global parameters knowledge with respect to existing alternatives, and can operate without any local Hessian inverse calculations nor Hessian communications. When solving personalized distributed learning formulations, DINAS achieves quadratic convergence with respect to computational cost and linear convergence with respect to communication cost, the latter rate being independent of the local functions condition numbers or of the network topology. When solving consensus optimization problems, DINAS is shown to converge to the global solution. Extensive numerical experiments demonstrate significant improvements of DINAS over existing alternatives. As a result of independent interest, we provide for the first time convergence analysis of the Newton method with the adaptive Polyak's step size when the Newton direction is computed inexactly in centralized environment.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"91 2","pages":"683-715"},"PeriodicalIF":1.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12085390/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144103095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marta Lazzaretti, Claudio Estatico, Alejandro Melero, Luca Calatroni
{"title":"Off-the-grid regularisation for Poisson inverse problems.","authors":"Marta Lazzaretti, Claudio Estatico, Alejandro Melero, Luca Calatroni","doi":"10.1007/s10589-025-00688-7","DOIUrl":"10.1007/s10589-025-00688-7","url":null,"abstract":"<p><p>Off-the-grid regularisation has been extensively employed over the last decade in the context of ill-posed inverse problems formulated in the continuous setting of the space of Radon measures <math><mrow><mi>M</mi> <mo>(</mo> <mi>Ω</mi> <mo>)</mo></mrow> </math> . These approaches enjoy convexity and counteract the discretisation biases as well the numerical instabilities typical of their discrete counterparts. In the framework of sparse reconstruction of discrete point measures (sum of weighted Diracs), a Total Variation regularisation norm in <math><mrow><mi>M</mi> <mo>(</mo> <mi>Ω</mi> <mo>)</mo></mrow> </math> is typically combined with an <math><msup><mi>L</mi> <mn>2</mn></msup> </math> data term modelling additive Gaussian noise. To assess the framework of off-the-grid regularisation in the presence of signal-dependent Poisson noise, we consider in this work a variational model where Total Variation regularisation is coupled with a Kullback-Leibler data term under a non-negativity constraint. Analytically, we study the optimality conditions of the composite functional and analyse its dual problem. Then, we consider an homotopy strategy to select an optimal regularisation parameter and use it within a Sliding Frank-Wolfe algorithm. Several numerical experiments on both 1D/2D/3D simulated and real 3D fluorescent microscopy data are reported.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"91 2","pages":"827-860"},"PeriodicalIF":1.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12085367/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144103167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A family of conjugate gradient methods with guaranteed positiveness and descent for vector optimization","authors":"Qing-Rui He, Sheng-Jie Li, Bo-Ya Zhang, Chun-Rong Chen","doi":"10.1007/s10589-024-00609-0","DOIUrl":"https://doi.org/10.1007/s10589-024-00609-0","url":null,"abstract":"<p>In this paper, we seek a new modification way to ensure the positiveness of the conjugate parameter and, based on the Dai-Yuan (DY) method in the vector setting, propose an associated family of conjugate gradient (CG) methods with guaranteed descent for solving unconstrained vector optimization problems. Several special members of the family are analyzed and the (sufficient) descent condition is established for them (in the vector sense). Under mild conditions, a general convergence result for the CG methods with specific parameters is presented, which, in particular, covers the global convergence of the aforementioned members. Furthermore, for the purpose of comparison, we then consider the direct extension versions of some Dai-Yuan type methods which are obtained by modifying the DY method of the scalar case. These vector extensions can retrieve the classical parameters in the scalar minimization case and their descent property and global convergence are also studied under mild assumptions. Finally, numerical experiments are given to illustrate the practical behavior of all proposed methods.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"47 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Convergence of a quasi-Newton method for solving systems of nonlinear underdetermined equations","authors":"N. Vater, A. Borzì","doi":"10.1007/s10589-024-00606-3","DOIUrl":"https://doi.org/10.1007/s10589-024-00606-3","url":null,"abstract":"<p>The development and convergence analysis of a quasi-Newton method for the solution of systems of nonlinear underdetermined equations is investigated. These equations arise in many application fields, e.g., supervised learning of large overparameterised neural networks, which require the development of efficient methods with guaranteed convergence. In this paper, a new approach for the computation of the Moore–Penrose inverse of the approximate Jacobian coming from the Broyden update is presented and a semi-local convergence result for a damped quasi-Newton method is proved. The theoretical results are illustrated in detail for the case of systems of multidimensional quadratic equations, and validated in the context of eigenvalue problems and supervised learning of overparameterised neural networks.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"91 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. A. Carrizo, N. S. Fazzio, M. D. Sánchez, M. L. Schuverdt
{"title":"Scaled-PAKKT sequential optimality condition for multiobjective problems and its application to an Augmented Lagrangian method","authors":"G. A. Carrizo, N. S. Fazzio, M. D. Sánchez, M. L. Schuverdt","doi":"10.1007/s10589-024-00605-4","DOIUrl":"https://doi.org/10.1007/s10589-024-00605-4","url":null,"abstract":"<p>Based on the recently introduced Scaled Positive Approximate Karush–Kuhn–Tucker condition for single objective problems, we derive a sequential necessary optimality condition for multiobjective problems with equality and inequality constraints as well as additional abstract set constraints. These necessary sequential optimality conditions for multiobjective problems are subject to the same requirements as ordinary (pointwise) optimization conditions: we show that the updated Scaled Positive Approximate Karush–Kuhn–Tucker condition is necessary for a local weak Pareto point to the problem. Furthermore, we propose a variant of the classical Augmented Lagrangian method for multiobjective problems. Our theoretical framework does not require any scalarization. We also discuss the convergence properties of our algorithm with regard to feasibility and global optimality without any convexity assumption. Finally, some numerical results are given to illustrate the practical viability of the method.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"59 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Newton-CG based barrier-augmented Lagrangian method for general nonconvex conic optimization","authors":"Chuan He, Heng Huang, Zhaosong Lu","doi":"10.1007/s10589-024-00603-6","DOIUrl":"https://doi.org/10.1007/s10589-024-00603-6","url":null,"abstract":"<p>In this paper we consider finding an approximate second-order stationary point (SOSP) of general nonconvex conic optimization that minimizes a twice differentiable function subject to nonlinear equality constraints and also a convex conic constraint. In particular, we propose a Newton-conjugate gradient (Newton-CG) based barrier-augmented Lagrangian method for finding an approximate SOSP of this problem. Under some mild assumptions, we show that our method enjoys a total inner iteration complexity of <span>({widetilde{{{,mathrm{mathcal {O}},}}}}(epsilon ^{-11/2}))</span> and an operation complexity of <span>({widetilde{{{,mathrm{mathcal {O}},}}}}(epsilon ^{-11/2}min {n,epsilon ^{-5/4}}))</span> for finding an <span>((epsilon ,sqrt{epsilon }))</span>-SOSP of general nonconvex conic optimization with high probability. Moreover, under a constraint qualification, these complexity bounds are improved to <span>({widetilde{{{,mathrm{mathcal {O}},}}}}(epsilon ^{-7/2}))</span> and <span>({widetilde{{{,mathrm{mathcal {O}},}}}}(epsilon ^{-7/2}min {n,epsilon ^{-3/4}}))</span>, respectively. To the best of our knowledge, this is the first study on the complexity of finding an approximate SOSP of general nonconvex conic optimization. Preliminary numerical results are presented to demonstrate superiority of the proposed method over first-order methods in terms of solution quality.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"165 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Robust approximation of chance constrained optimization with polynomial perturbation","authors":"Bo Rao, Liu Yang, Suhan Zhong, Guangming Zhou","doi":"10.1007/s10589-024-00602-7","DOIUrl":"https://doi.org/10.1007/s10589-024-00602-7","url":null,"abstract":"<p>This paper proposes a robust approximation method for solving chance constrained optimization (CCO) of polynomials. Assume the CCO is defined with an individual chance constraint that is affine in the decision variables. We construct a robust approximation by replacing the chance constraint with a robust constraint over an uncertainty set. When the objective function is linear or SOS-convex, the robust approximation can be equivalently transformed into linear conic optimization. Semidefinite relaxation algorithms are proposed to solve these linear conic transformations globally and their convergent properties are studied. We also introduce a heuristic method to find efficient uncertainty sets such that optimizers of the robust approximation are feasible to the original problem. Numerical experiments are given to show the efficiency of our method.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"42 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A power-like method for finding the spectral radius of a weakly irreducible nonnegative symmetric tensor","authors":"Xueli Bai, Dong-Hui Li, Lei Wu, Jiefeng Xu","doi":"10.1007/s10589-024-00601-8","DOIUrl":"https://doi.org/10.1007/s10589-024-00601-8","url":null,"abstract":"<p>The Perron–Frobenius theorem says that the spectral radius of a weakly irreducible nonnegative tensor is the unique positive eigenvalue corresponding to a positive eigenvector. With this fact in mind, the purpose of this paper is to find the spectral radius and its corresponding positive eigenvector of a weakly irreducible nonnegative symmetric tensor. By transforming the eigenvalue problem into an equivalent problem of minimizing a concave function on a closed convex set, we derive a simpler and cheaper iterative method called power-like method, which is well-defined. Furthermore, we show that both sequences of the eigenvalue estimates and the eigenvector evaluations generated by the power-like method <i>Q</i>-linearly converge to the spectral radius and its corresponding eigenvector, respectively. To accelerate the method, we introduce a line search technique. The improved method retains the same convergence property as the original version. Plentiful numerical results show that the improved method performs quite well.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"46 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An inexact regularized proximal Newton method without line search","authors":"Simeon vom Dahl, Christian Kanzow","doi":"10.1007/s10589-024-00600-9","DOIUrl":"https://doi.org/10.1007/s10589-024-00600-9","url":null,"abstract":"<p>In this paper, we introduce an inexact regularized proximal Newton method (IRPNM) that does not require any line search. The method is designed to minimize the sum of a twice continuously differentiable function <i>f</i> and a convex (possibly non-smooth and extended-valued) function <span>(varphi )</span>. Instead of controlling a step size by a line search procedure, we update the regularization parameter in a suitable way, based on the success of the previous iteration. The global convergence of the sequence of iterations and its superlinear convergence rate under a local Hölderian error bound assumption are shown. Notably, these convergence results are obtained without requiring a global Lipschitz property for <span>( nabla f )</span>, which, to the best of the authors’ knowledge, is a novel contribution for proximal Newton methods. To highlight the efficiency of our approach, we provide numerical comparisons with an IRPNM using a line search globalization and a modern FISTA-type method.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"29 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142199607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Serge Gratton, Valentin Mercier, Elisa Riccietti, Philippe L. Toint
{"title":"A block-coordinate approach of multi-level optimization with an application to physics-informed neural networks","authors":"Serge Gratton, Valentin Mercier, Elisa Riccietti, Philippe L. Toint","doi":"10.1007/s10589-024-00597-1","DOIUrl":"https://doi.org/10.1007/s10589-024-00597-1","url":null,"abstract":"<p>Multi-level methods are widely used for the solution of large-scale problems, because of their computational advantages and exploitation of the complementarity between the involved sub-problems. After a re-interpretation of multi-level methods from a block-coordinate point of view, we propose a multi-level algorithm for the solution of nonlinear optimization problems and analyze its evaluation complexity. We apply it to the solution of partial differential equations using physics-informed neural networks (PINNs) and consider two different types of neural architectures, a generic feedforward network and a frequency-aware network. We show that our approach is particularly effective if coupled with these specialized architectures and that this coupling results in better solutions and significant computational savings.</p>","PeriodicalId":55227,"journal":{"name":"Computational Optimization and Applications","volume":"58 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141944946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}