Integer Programming

Piecewise Polyhedral Relaxations of Multilinear Optimization

  • Jongeun Kim
  • Jean-Philippe P. Richard
  • Mohit Tawarmalani
    • Categories (Mixed) Integer Nonlinear Programming, Global Optimization Tags , , ,

    In this paper, we consider piecewise polyhedral relaxations (PPRs) of multilinear optimization problems over axis-parallel hyper-rectangular partitions of their domain. We improve formulations for PPRs by linking components that are commonly modeled independently in the literature. Numerical experiments with ALPINE, an open-source software for global optimization that relies on piecewise approximations of functions, show that … Read more

    A Stochastic Optimization Approach to Energy-Efficient Underground Timetabling under Uncertain Dwell and Running Times

  • Patrick Gemander
  • Andreas Bärmann
  • Alexander Martin
    • Categories (Mixed) Integer Linear Programming, Stochastic Programming, Transportation Tags , , , , ,

    We consider a problem from the context of energy-efficient underground railway timetabling, in which an existing timetable draft is improved by slightly changing departure and running times. In practice, synchronization between accelerating and braking trains to utilize regenerative braking plays a major role for the energy-efficiency of a timetable. Since deviations from a planned timetable … Read more

    A combined model for chain expansion including the possibility of locating a new facility and modification and/or closing of existing facilities

  • Boglárka Tóth
  • Laura Anton-Sanchez
  • José Fernández
    • Categories (Mixed) Integer Linear Programming, Facility Planning and Design, Global Optimization Applications Tags , , , ,

    The problem of an expanding chain (it already has some facilities) in a given area is considered. It may locate a new facility, or vary (up or down) the quality of its existing facilities, or close some of them, or a combination of all those possibilities, whatever it is the best to maximize its profit, … Read more

    The role of rationality in integer-programming relaxations

  • Manuel Aprile
  • Gennadiy Averkov
  • Marco Di Summa
  • Christopher Hojny
    • Categories Integer Programming Tags , ,

    For a finite set $X \subset \Z^d$ that can be represented as $X = Q \cap \Z^d$ for some polyhedron $Q$, we call $Q$ a relaxation of $X$ and define the relaxation complexity $\rc(X)$ of $X$ as the least number of facets among all possible relaxations $Q$ of $X$. The rational relaxation complexity $\rc_\Q(X)$ restricts … Read more

    Learning to Use Local Cuts

  • Timo Berthold
  • Matteo Francobaldi
  • Gregor Hendel
    • Categories (Mixed) Integer Linear Programming, Optimization Software Design Principles Tags , ,

    An essential component in modern solvers for mixed-integer (linear) programs (MIPs) is the separation of additional inequalities (cutting planes) to tighten the linear programming relaxation. Various algorithmic decisions are necessary when integrating cutting plane methods into a branch-and-bound (B&B) solver as there is always the trade-off between the efficiency of the cuts and their costs, … Read more

    Lexicographic Branch-and-Bound Column Search

  • Andreas Bärmann
  • Alexander Müller
  • Dieter Weninger
    • Categories (Mixed) Integer Linear Programming, Linear Programming, Scheduling Tags , , , , ,

    We present an exact generic method for solving the pricing problem in a column generation approach, which we call branch-and-bound column search. It searches the space of all feasible columns via a branch-and-bound tree search and returns all columns with a reduced-cost value below a certainthreshold. The approach is based on an idea from Krumke … Read more

    Solving large-scale unit-commitment problems using dual dynamic programming and open-source solvers

  • Bruno Colonetti
  • Samuel Brito
  • Erlon Finardi
  • Victor M. Zavala
  • Lucas Picarelli
    • Categories 0-1 Programming, Applications - Science and Engineering, Dynamic Programming Tags , , ,

    The astonishing dimensions and complexity of power systems render them impossible to be managed without the help of cutting-edge software. Due to a lack of scalable, reliable and well documented free and open-source solutions, system operators, regulators, and government agencies often rely on proprietary software to provide them information that ultimately will be used to … Read more

    DiversiTree: A New Method to Efficiently Compute Diverse Sets of Near-Optimal Solutions to Mixed-Integer Optimization Problems

  • Izuwa Ahanor
  • Hugh R. Medal
  • Andrew C. Trapp
    • Categories Applications - Science and Engineering, Integer Programming, Other Topics Tags , , ,

    While most methods for solving mixed-integer optimization problems compute a single optimal solution, a diverse set of near-optimal solutions can often lead to improved outcomes. We present a new method for finding a set of diverse solutions by emphasizing diversity within the search for near-optimal solutions. Specifically, within a branch-and-bound framework, we investigated parameterized node … Read more

    Logic-based Benders decomposition with a partial assignment acceleration technique for avionics scheduling

  • Emil Karlsson
  • Elina Rönnberg
    • Categories (Mixed) Integer Linear Programming Tags , , , , ,

    Pre-runtime scheduling of large-scale electronic systems, as those in modern aircraft, can be computationally challenging. In this paper, we study a distributed integrated modular avionic system of practical relevance where the scheduling includes to assign communication messages to time slots and to sequence tasks on modules. For this problem, the challenge is the huge number … Read more

    A new family of route formulations for split delivery vehicle routing problems

  • Isaac Balster
  • Teobaldo Bulhões
  • Pedro Munari
  • Artur Alves Pessoa
  • Ruslan Sadykov
    • Categories Combinatorial Optimization, Integer Programming, Transportation Tags , , , ,

    We propose a new family of formulations with route-based variables for the split delivery vehicle routing problem with and without time windows. Each formulation in this family is characterized by the maximum number of different demand quantities that can be delivered to a customer during a vehicle visit. As opposed to previous formulations in the … Read more