Constrained Nonlinear Optimization

Combining segment generation with direct step-and-shoot optimization in intensity-modulated radiation therapy

  • Fredrik Carlsson
    • Categories Biomedical Applications, Constrained Nonlinear Optimization Tags , , ,

    A method for generating a sequence of intensity-modulated radiation therapy step-and-shoot plans with increasing number of segments is presented. The objectives are to generate high-quality plans with few, large and regular segments, and to make the planning process more intuitive. The proposed method combines segment generation with direct step-and-shoot optimization, where leaf positions and segment … Read more

    On the solution of fuzzy bilevel programming problems

  • Stephan Dempe
  • Tatiana Starostina
    • Categories Constrained Nonlinear Optimization, Game Theory

    In this paper we formulate the fuzzy bilevel programming problem and describe one possible approach for formulating a crisp optimization problem being attached to it. Due to the nature of fuzzy bilevel programming this is a crisp bilevel programming problem. We compare our approach with one using multicriterial optimization and show, that both approaches are … Read more

    A Filter Active-Set Trust-Region Method

  • Michael P. Friedlander
  • Nicholas I. M. Gould
  • Sven Leyffer
  • Todd S. Munson
    • Categories Constrained Nonlinear Optimization, Nonlinear Optimization Tags , ,

    We develop a new active-set method for nonlinear programming problems that solves a regularized linear program to predict the active set and then fixes the active constraints to solve an equality-constrained quadratic program for fast convergence. Global convergence is promoted through the use of a filter. We show that the regularization parameter fulfills the same … Read more

    Optimization by the Fixed-Point Method, Version 2.17

  • Jalaluddin Abdullah
    • Categories Constrained Nonlinear Optimization, Linear Programming Tags , , ,

    Abstract: After developing necessary background theory, the original primal and dual are specified, and the invariant primal and dual LP’s are defined. Pairs of linear mappings are defined which establish an effectively one-to-one correspondences between solutions to the original and invariant problems. The invariant problems are recast as a fixed-point problem and precise solution conditions … Read more

    The extremal volume ellipsoids of convex bodies, their symmetry properties, and their determination in some special cases

  • Osman Guler
  • Filiz Gurtuna
    • Categories Constrained Nonlinear Optimization, Convex Optimization, Semi-infinite Programming Tags , , , , , , , , , , ,

    A convex body K has associated with it a unique circumscribed ellipsoid CE(K) with minimum volume, and a unique inscribed ellipsoid IE(K) with maximum volume. We first give a unified, modern exposition of the basic theory of these extremal ellipsoids using the semi-infinite programming approach pioneered by Fritz John in his seminal 1948 paper. We … Read more

    An Active-Set Algorithm for Nonlinear Programming Using Parametric Linear Programming

  • Richard H. Byrd
  • Richard A. Waltz
    • Categories Constrained Nonlinear Optimization Tags , , ,

    This paper describes an active-set algorithm for nonlinear programming that solves a parametric linear programming subproblem at each iteration to generate an estimate of the active set. A step is then computed by solving an equality constrained quadratic program based on this active-set estimate. This approach respresents an extension of the standard sequential linear-quadratic programming … Read more

    Local convergence for alternating and averaged nonconvex projections

  • Adrian Lewis
  • Jérôme Malick
  • Russell Luke
    • Categories Constrained Nonlinear Optimization, Control Applications, Nonsmooth Optimization Tags , , , , , , , ,

    The idea of a finite collection of closed sets having “strongly regular intersection” at a given point is crucial in variational analysis. We show that this central theoretical tool also has striking algorithmic consequences. Specifically, we consider the case of two sets, one of which we assume to be suitably “regular” (special cases being convex … Read more

    The Squared Slacks Transformation in Nonlinear Programming

  • Paul Armand
  • Dominique Orban
    • Categories Constrained Nonlinear Optimization Tags , ,

    We recall the use of squared slacks used to transform inequality constraints into equalities and several reasons why their introduction may be harmful in many algorithmic frameworks routinely used in nonlinear programming. Numerical examples performed with the sequential quadratic programming method illustrate those reasons. CitationCahier du GERAD G-2007-62, Aug. 2007ArticleDownload View PDF

    An Inexact Newton Method for Nonconvex Equality Constrained Optimization

  • Richard H. Byrd
  • Frank E. Curtis
  • Jorge Nocedal
    • Categories Constrained Nonlinear Optimization, Nonlinear Optimization, Systems governed by Differential Equations Optimization Tags , , , ,

    We present a matrix-free line search algorithm for large-scale equality constrained optimization that allows for inexact step computations. For strictly convex problems, the method reduces to the inexact sequential quadratic programming approach proposed by Byrd et al. [SIAM J. Optim. 19(1) 351–369, 2008]. For nonconvex problems, the methodology developed in this paper allows for the … Read more

    DIRECT SEARCH ALGORITHMS OVER RIEMANNIAN MANIFOLDS

  • David W. Dreisigmeyer
    • Categories Constrained Nonlinear Optimization Tags , , , ,

    We generalize the Nelder-Mead simplex and LTMADS algorithms and, the frame based methods for function minimization to Riemannian manifolds. Examples are given for functions defined on the special orthogonal Lie group $\mathcal{SO}(n)$ and the Grassmann manifold $\mathcal{G}(n,k)$. Our main examples are applying the generalized LTMADS algorithm to equality constrained optimization problems and, to the Whitney … Read more