Roberto Andreani

On sequential optimality conditions for smooth constrained optimization

  • Roberto Andreani
  • Gabriel Haeser
  • José Mario Martínez
    • Categories Nonlinear Optimization Tags , , ,

    Sequential optimality conditions provide adequate theoretical tools to justify stopping criteria for nonlinear programming solvers. Approximate KKT and Approximate Gradient Projection conditions are analyzed in this work. These conditions are not necessarily equivalent. Implications between different conditions and counter-examples will be shown. Algorithmic consequences will be discussed. Article Download View On sequential optimality conditions for … Read more

    The Constant Rank Condition and Second Order Constraint Qualifications

  • Roberto Andreani
  • Carlos Eugenio Echagüe
  • María Laura Schuverdt
    • Categories Nonlinear Optimization Tags ,

    The Constant Rank condition for feasible points of nonlinear programming problems was defined by Janin in Ref. 1. In that paper the author proved that the condition was a first order constraint qualification. In this work we prove that the Janin Constant Rank condition is, in addition, a second order constraint qualification. We also define … Read more

    On Second-Order Optimality Conditions for Nonlinear Programming

  • Roberto Andreani
  • José Mario Martínez
  • María Laura Schuverdt
    • Categories Constrained Nonlinear Optimization Tags ,

    Necessary Optimality Conditions for Nonlinear Programming are discussed in the present research. A new Second-Order condition is given, which depends on a weak constant rank constraint requirement. We show that practical and publicly available algorithms (www.ime.usp.br/~egbirgin/tango) of Augmented Lagrangian type converge, after slight modifications, to stationary points defined by the new condition. Article Download View … Read more

    Continuous Optimization Methods for Structure Alignments

  • Roberto Andreani
  • Leandro Martínez
  • José Mario Martínez
  • Flavio Yano
    • Categories Basic Sciences Applications, Nonlinear Optimization Tags , , , ,

    Structural Alignment is an important tool for fold identification of proteins, structural screening on ligand databases, pharmacophore identification and other applications. In the general case, the optimization problem of superimposing two structures is nonsmooth and nonconvex, so that most popular methods are heuristic and do not employ derivative information. Usually, these methods do not admit … Read more

    Low Order-Value Optimization and Applications

  • Roberto Andreani
  • Leandro Martínez
  • José Mario Martínez
  • Flavio Yano
    • Categories Applications - OR and Management Sciences, Applications - Science and Engineering, Nonlinear Optimization Tags , , ,

    Given r real functions F1 (x), . . . , Fr (x) and an integer p between 1 and r, the Low Order- Value Optimization problem (LOVO) consists of minimizing the sum of the functions that take the p smaller values. If (y1 , . . . , yr ) is a vector of data … Read more

    On Augmented Lagrangian methods with general lower-level constraints

  • Roberto Andreani
  • Ernesto G. Birgin
  • José Mario Martínez
  • María Laura Schuverdt
    • Categories Constrained Nonlinear Optimization, Nonlinear Optimization Tags , , , ,

    Augmented Lagrangian methods with general lower-level constraints are considered in the present research. These methods are useful when efficient algorithms exist for solving subproblems where the constraints are only of the lower-level type. Two methods of this class are introduced and analyzed. Inexact resolution of the lower-level constrained subproblems is considered. Global convergence is proved … Read more

    Nonlinear-Programming Reformulation of the Order-Value Optimization problem

  • Roberto Andreani
  • José Mario Martínez
  • Cibele Dunder
    • Categories Nonlinear Optimization Tags , , , ,

    Order-value optimization (OVO) is a generalization of the minimax problem motivated by decision-making problems under uncertainty and by robust estimation. New optimality conditions for this nonsmooth optimization problem are derived. An equivalent mathematical programming problem with equilibrium constraints is deduced. The relation between OVO and this nonlinear-programming reformulation is studied. Particular attention is given to … Read more

    Augmented Lagrangian methods under the Constant Positive Linear Dependence constraint qualification

  • Roberto Andreani
  • Ernesto G. Birgin
  • José Mario Martínez
  • María Laura Schuverdt
    • Categories Nonlinear Optimization Tags , , ,

    Two Augmented Lagrangian algorithms for solving KKT systems are introduced. The algorithms differ in the way in which penalty parameters are updated. Possibly infeasible accumulation points are characterized. It is proved that feasible limit points that satisfy the Constant Positive Linear Dependence constraint qualification are KKT solutions. Boundedness of the penalty parameters is proved under … Read more