Gonzalo Muñoz

Decision-focused predictions via pessimistic bilevel optimization: complexity and algorithms

  • Victor Bucarey
  • Sophia Calderón
  • Gonzalo Muñoz
  • Frédéric Semet
    • Categories Constrained Nonlinear Optimization, Data Science Applications, Other Topics Tags ,

    Dealing with uncertainty in optimization parameters is an important and longstanding challenge. Typically, uncertain parameters are predicted accurately, and then a deterministic optimization problem is solved. However, the decisions produced by this so-called {\it predict-then-optimize} procedure can be highly sensitive to uncertain parameters. In this work, we contribute to recent efforts in producing {\it decision-focused} … Read more

    The MIP Workshop 2023 Computational Competition on Reoptimization

  • Suresh Bolusani
  • Mathieu Besançon
  • Ambros Gleixner
  • Timo Berthold
  • Claudia D'Ambrosio
  • Gonzalo Muñoz
  • Joseph Paat
  • Dimitri Thomopulos
    • Categories Combinatorial Optimization, Integer Programming, Optimization Software and Modeling Systems Tags , , , ,

    This paper describes the computational challenge developed for a computational competition held in 2023 for the 20th anniversary of the Mixed Integer Programming Workshop. The topic of this competition was reoptimization, also known as warm starting, of mixed integer linear optimization problems after slight changes to the input data for a common formulation. The challenge … Read more

    When Deep Learning Meets Polyhedral Theory: A Survey

  • Joey Huchette
  • Gonzalo Muñoz
  • Thiago Serra
  • Calvin Tsay
    • Categories (Mixed) Integer Linear Programming, Optimization in Data Science, Polyhedra

    In the past decade, deep learning became the prevalent methodology for predictive modeling thanks to the remarkable accuracy of deep neural networks in tasks such as computer vision and natural language processing. Meanwhile, the structure of neural networks converged back to simpler representations based on piecewise constant and piecewise linear functions such as the Rectified … Read more

    On obtaining the convex hull of quadratic inequalities via aggregations

  • Santanu S. Dey
  • Felipe Serrano
  • Gonzalo Muñoz
    • Categories Global Optimization Theory Tags , ,

    A classical approach for obtaining valid inequalities for a set involves weighted aggregations of the inequalities that describe such set. When the set is described by linear inequalities, thanks to the Farkas lemma, we know that every valid inequality can be obtained using aggregations. When the inequalities describing the set are two quadratics, Yildiran showed … Read more

    Cutting Plane Generation Through Sparse Principal Component Analysis

  • Santanu S. Dey
  • Aleksandr M. Kazachkov
  • Andrea Lodi
  • Gonzalo Muñoz
    • Categories Cutting Plane Approaches, Quadratic Programming Tags , , ,

    Quadratically-constrained quadratic programs (QCQPs) are optimization models whose remarkable expressiveness has made them a cornerstone of methodological research for nonconvex optimization problems. However, modern methods to solve a general QCQP fail to scale, encountering computational challenges even with just a few hundred variables. Specifically, a semidefinite programming (SDP) relaxation is typically employed, which provides strong … Read more

    On Generalized Surrogate Duality in Mixed-Integer Nonlinear Programming

  • Maxime Gasse
  • Ambros Gleixner
  • Andrea Lodi
  • Felipe Serrano
  • Benjamin Müller
  • Gonzalo Muñoz
    • Categories (Mixed) Integer Nonlinear Programming, Global Optimization, Nonlinear Optimization Tags ,

    The most important ingredient for solving mixed-integer nonlinear programs (MINLPs) to global epsilon-optimality with spatial branch and bound is a tight, computationally tractable relaxation. Due to both theoretical and practical considerations, relaxations of MINLPs are usually required to be convex. Nonetheless, current optimization solver can often successfully handle a moderate presence of nonconvexities, which opens … Read more

    Outer-Product-Free Sets for Polynomial Optimization and Oracle-Based Cuts

  • Daniel Bienstock
  • Chen Chen
  • Gonzalo Muñoz
    • Categories Constrained Nonlinear Optimization, Cutting Plane Approaches, Global Optimization Theory Tags , ,

    Cutting planes are derived from specific problem structures, such as a single linear constraint from an integer program. This paper introduces cuts that involve minimal structural assumptions, enabling the generation of strong polyhedral relaxations for a broad class of problems. We consider valid inequalities for the set $S\cap P$, where $S$ is a closed set, … Read more

    LP formulations for mixed-integer polynomial optimization problems

  • Daniel Bienstock
  • Gonzalo Muñoz
    • Categories (Mixed) Integer Nonlinear Programming, Nonsmooth Optimization Tags

    We present polynomial-time algorithms for constrained optimization problems overwhere the intersection graph of the constraint set has bounded tree-width. In the case of binary variables we obtain exact, polynomial-size linear programming formulations for the problem. In the mixed-integer case with bounded variables we obtain polynomial-size linear programming representations that attain guaranteed optimality and feasibility bounds. … Read more