stochastic optimization

Zeroth-order Nonconvex Stochastic Optimization: Handling Constraints, High-Dimensionality, and Saddle-Points

  • Krishnakumar Balasubramanian
  • Saeed Ghadimi
    • Categories Nonlinear Optimization, Stochastic Programming Tags , , , , ,

    In this paper, we propose and analyze zeroth-order stochastic approximation algorithms for nonconvex and convex optimization, with a focus on addressing constrained optimization, high-dimensional setting, and saddle-point avoiding. To handle constrained optimization, we first propose generalizations of the conditional gradient algorithm achieving rates similar to the standard stochastic gradient algorithm using only zeroth-order information. To … Read more

    Reinforcement Learning via Parametric Cost Function Approximation for Multistage Stochastic Programming

  • Saeed Ghadimi
  • Raymond Perkins
  • Warren B. Powell
    • Categories Applications - OR and Management Sciences, Optimization of Simulated Systems, Stochastic Programming Tags , , , ,

    The most common approaches for solving stochastic resource allocation problems in the research literature is to either use value functions (“dynamic programming”) or scenario trees (“stochastic programming”) to approximate the impact of a decision now on the future. By contrast, common industry practice is to use a deterministic approximation of the future which is easier … Read more

    Large-scale Influence Maximization via Maximal Covering Location

  • Evren Güney
  • Markus Leitner
  • Mario Ruthmair
  • Markus Sinnl
    • Categories Applications - OR and Management Sciences, Integer Programming, Stochastic Programming Tags , , ,

    Influence maximization aims at identifying a limited set of key individuals in a (social) network which spreads information based on some propagation model and maximizes the number of individuals reached. We show that influence maximization based on the probabilistic independent cascade model can be modeled as a stochastic maximal covering location problem. A reformulation based … Read more

    Data-Driven Maintenance and Operations Scheduling in Power Systems under Decision-Dependent Uncertainty

  • Shabbir Ahmed
  • Nagi Gebraeel
  • Beste Basciftci
    • Categories Applications - OR and Management Sciences, Applications - Science and Engineering Tags , , ,

    Generator maintenance scheduling plays a pivotal role in ensuring uncompromising operations of power systems. There exists a tight coupling between the condition of the generators and corresponding operational schedules, significantly affecting reliability of the system. In this study, we effectively model and solve an integrated condition-based maintenance and operations scheduling problem for a fleet of … Read more

    Improving the Flexibility and Robustness of Model-Based Derivative-Free Optimization Solvers

  • Coralia Cartis
  • Jan Fiala
  • Benjamin Marteau
  • Lindon Roberts
    • Categories Nonlinear Optimization Tags , , , , ,

    We present DFO-LS, a software package for derivative-free optimization (DFO) for nonlinear Least-Squares (LS) problems, with optional bound constraints. Inspired by the Gauss-Newton method, DFO-LS constructs simplified linear regression models for the residuals. DFO-LS allows flexible initialization for expensive problems, whereby it can begin making progress from as few as two objective evaluations. Numerical results … Read more

    Derivative-Free Optimization of Noisy Functions via Quasi-Newton Methods

  • Albert S. Berahas
  • Richard H. Byrd
  • Jorge Nocedal
    • Categories Nonlinear Optimization, Unconstrained Optimization Tags , ,

    This paper presents a finite difference quasi-Newton method for the minimization of noisy functions. The method takes advantage of the scalability and power of BFGS updating, and employs an adaptive procedure for choosing the differencing interval h based on the noise estimation techniques of Hamming (2012) and Moré and Wild (2011). This noise estimation procedure … Read more

    A Progressive Batching L-BFGS Method for Machine Learning

  • Raghu Bollapragada
  • Jorge Nocedal
  • Hao-Jun Shi
  • Ping Tak Peter Tang
  • Dheevatsa Mudigere
    • Categories Convex Optimization, Nonlinear Optimization, Stochastic Programming Tags , , ,

    The standard L-BFGS method relies on gradient approximations that are not dominated by noise, so that search directions are descent directions, the line search is reliable, and quasi-Newton updating yields useful quadratic models of the objective function. All of this appears to call for a full batch approach, but since small batch sizes give rise … Read more

    A Stochastic Trust Region Algorithm Based on Careful Step Normalization

  • Frank E. Curtis
  • Katya Scheinberg
  • Rui Shi
    • Categories Nonlinear Optimization, Stochastic Programming, Unconstrained Optimization Tags , , , , , ,

    An algorithm is proposed for solving stochastic and finite sum minimization problems. Based on a trust region methodology, the algorithm employs normalized steps, at least as long as the norms of the stochastic gradient estimates are within a specified interval. The complete algorithm—which dynamically chooses whether or not to employ normalized steps—is proved to have … Read more

    Random Gradient Extrapolation for Distributed and Stochastic Optimization

  • Guanghui Lan
  • Yi Zhou
    • Categories Convex Optimization, Stochastic Programming Tags , , , ,

    In this paper, we consider a class of finite-sum convex optimization problems defined over a distributed multiagent network with $m$ agents connected to a central server. In particular, the objective function consists of the average of $m$ ($\ge 1$) smooth components associated with each network agent together with a strongly convex term. Our major contribution … Read more

    Computational Aspects of Bayesian Solution Estimators in Stochastic Optimization

  • Gérard Cornuéjols
  • Danial Davarnia
  • Burak Kocuk
    • Categories Statistics, Stochastic Approaches, Stochastic Programming Tags , , , ,

    We study a class of stochastic programs where some of the elements in the objective function are random, and their probability distribution has unknown parameters. The goal is to find a good estimate for the optimal solution of the stochastic program using data sampled from the distribution of the random elements. We investigate two common … Read more