Nonlinear Optimization

Towards robust optimal control of chromatographic separation processes with controlled flow reversal

  • Dominik H. Cebulla
  • Christian Kirches
  • Andreas Potschka
    • Categories Chemical Engineering, Robust Optimization, Systems governed by Differential Equations Optimization Tags , ,

    Column liquid chromatography is an important technique applied in the production of biopharmaceuticals, specifically for the separation of biological macromolecules such as proteins. When setting up process conditions, it is crucial that the purity of the product is sufficiently high, even in the presence of perturbations in the process conditions, e.g., altered buffer salt concentrations. … Read more

    On the Complexity of Lower-Order Implementations of Higher-Order Methods

  • Nikita Doikov
  • Geovani Nunes Grapiglia
    • Categories Nonlinear Optimization Tags , , , ,

    In this work, we propose a method for minimizing non-convex functions with Lipschitz continuous \(p\)th-order derivatives, starting from \(p \geq 1\). The method, however, only requires derivative information up to order \((p-1)\), since the \(p\)th-order derivatives are approximated via finite differences. To ensure oracle efficiency, instead of computing finite-difference approximations at every iteration, we reuse … Read more

    A Simple Adaptive Proximal Gradient Method for Nonconvex Optimization

  • Ye Zilong
  • Shiqian Ma
  • Junfeng Yang
  • Danqing Zhou
    • Categories Constrained Nonlinear Optimization, Nonsmooth Optimization Tags , , , ,

    Consider composite nonconvex optimization problems where the objective function consists of a smooth nonconvex term (with Lipschitz-continuous gradient) and a convex (possibly nonsmooth) term. Existing parameter-free methods for such problems often rely on complex multi-loop structures, require line searches, or depend on restrictive assumptions (e.g., bounded iterates). To address these limitations, we introduce a novel … Read more

    MadNCL: A GPU Implementation of Algorithm NCL for Large-Scale, Degenerate Nonlinear Programs

  • François Pacaud
  • Alexis Montoison
  • Dominique Orban
  • Sungho Shin
  • Michael A. Saunders
    • Categories Constrained Nonlinear Optimization, Nonlinear Optimization

    We present a GPU implementation of Algorithm NCL, an augmented Lagrangian method for solving large-scale and degenerate nonlinear programs. Although interior-point methods and sequential quadratic programming are widely used for solving nonlinear programs, the augmented Lagrangian method is known to offer superior robustness against constraint degeneracies and can rapidly detect infeasibility. We introduce several enhancements … Read more

    Continuous-time Analysis of a Stochastic ADMM Method for Nonconvex Composite Optimization

  • Jiahong Guo
  • Xiao Wang
  • Xiantao Xiao
    • Categories Nonlinear Optimization, Unconstrained Optimization

    In this paper, we focus on nonconvex composite optimization, whose objective is the sum of a smooth but possibly nonconvex function and a composition of a weakly convex function coupled with a linear operator. By leveraging a smoothing technique based on Moreau envelope, we propose a stochastic proximal linearized ADMM algorithm (SPLA). To understand its … Read more

    Progressively Sampled Equality-Constrained Optimization

  • Frank E. Curtis
  • Lingjun Guo
  • Daniel P. Robinson
    • Categories Constrained Nonlinear Optimization, Nonlinear Optimization, Optimization in Data Science Tags , , , ,

    An algorithm is proposed, analyzed, and tested for solving continuous nonlinear-equality-constrained optimization problems where the constraints are defined by an expectation or an average over a large (finite) number of terms. The main idea of the algorithm is to solve a sequence of equality-constrained problems, each involving a finite sample of constraint-function terms, over which … Read more

    A Riemannian AdaGrad-Norm Method

  • Glaydston Bento
  • Geovani Nunes Grapiglia
  • Mauricio Louzeiro
  • Daoping Zhang
    • Categories Generalized Convexity/Monoticity, Global Optimization Applications, Nonlinear Optimization Tags , , , ,

    We propose a manifold AdaGrad-Norm method (\textsc{MAdaGrad}), which extends the norm version of AdaGrad (AdaGrad-Norm) to Riemannian optimization. In contrast to line-search schemes, which may require several exponential map computations per iteration, \textsc{MAdaGrad} requires only one. Assuming the objective function $f$ has Lipschitz continuous Riemannian gradient, we show that the method requires at most $\mathcal{O}(\varepsilon^{-2})$ … Read more

    On the Convergence and Properties of a Proximal-Gradient Method on Hadamard Manifolds

  • Glaydston Bento
  • Claudemir Rodrigues Santiago
    • Categories Constrained Nonlinear Optimization, Global Optimization Theory, Nonsmooth Optimization Tags , , ,

    In this paper, we address composite optimization problems on Hadamard manifolds, where the objective function is given by the sum of a smooth term (not necessarily convex) and a convex term (not necessarily differentiable). To solve this problem, we develop a proximal gradient method defined directly on the manifold, employing a strategy that enforces monotonicity … Read more

    Machine Learning Algorithms for Improving Black Box Optimization Solvers

  • Morteza Kimiaei
  • Vyacheslav Kungurtsev
    • Categories Global Optimization, Nonlinear Optimization, Optimization in Data Science Tags , , , , ,

    Black-box optimization (BBO) addresses problems where objectives are accessible only through costly queries without gradients or explicit structure. Classical derivative-free methods—line search, direct search, and model-based solvers such as Bayesian optimization—form the backbone of BBO, yet often struggle in high-dimensional, noisy, or mixed-integer settings. Recent advances use machine learning (ML) and reinforcement learning (RL) to … Read more

    Sequential test sampling for stochastic derivative-free optimization

  • Anjie Ding
  • Francesco Rinaldi
  • Luis Nunes Vicente
    • Categories Nonlinear Optimization Tags , , ,

    In many derivative-free optimization algorithms, a sufficient decrease condition decides whether to accept a trial step in each iteration. This condition typically requires that the potential objective function value decrease of the trial step, i.e., the true reduction in the objective function value that would be achieved by moving from the current point to the … Read more