(Mixed) Integer Linear Programming

There’s No Free Lunch: On the Hardness of Choosing a Correct Big-M in Bilevel Optimization

  • Thomas Kleinert
  • Martine Labbé
  • Martin Schmidt
  • Fränk Plein
    • Categories (Mixed) Integer Linear Programming, Complementarity and Variational Inequalities Tags , , , ,

    One of the most frequently used approaches to solve linear bilevel optimization problems consists in replacing the lower-level problem with its Karush-Kuhn-Tucker (KKT) conditions and by reformulating the KKT complementarity conditions using techniques from mixed-integer linear optimization. The latter step requires to determine some big-M constant in order to bound the lower level’s dual feasible … Read more

    Integer Programming for Learning Directed Acyclic Graphs from Continuous Data

  • Simge Küçükyavuz
  • Hasan Manzour
  • Ali Shojaie
  • Hao-Hsiang Wu
    • Categories (Mixed) Integer Linear Programming, Statistics Tags , , ,

    Learning directed acyclic graphs (DAGs) from data is a challenging task both in theory and in practice, because the number of possible DAGs scales superexponentially with the number of nodes. In this paper, we study the problem of learning an optimal DAG from continuous observational data. We cast this problem in the form of a … Read more

    Multi-objective optimization models for many-to-one matching problems

  • Natsumi Shimada
  • Yuichi Takano
  • Natsuki Yamazaki
    • Categories (Mixed) Integer Linear Programming, Finance and Economics Tags , , , ,

    This paper is concerned with many-to-one matching problems for assigning residents to hospitals according to their preferences. The stable matching model aims at finding a stable matching, and the assignment game model involves maximizing the total utility; however, these two objectives are incompatible in general. We also focus on a situation where there are predetermined … Read more

    An Iterative Graph Expansion Approach for the Scheduling and Routing of Airplanes

  • Armin Fügenschuh
  • Fabian Gnegel
    • Categories (Mixed) Integer Linear Programming, Branch and Cut Algorithms, Transportation Tags , , ,

    A tourism company that offers fly-in safaris is faced with the challenge to route and schedule its fleet of airplanes in an optimal way. Over the course of a given time horizon several groups of tourists have to be picked up at airports and flown to their destinations within a certain time-window. Furthermore the number … Read more

    Structure-driven fix-and-propagate heuristics for mixed integer programming

  • Timo Berthold
  • Gerald Gamrath
  • Stefan Heinz
  • Michael Winkler
    • Categories (Mixed) Integer Linear Programming Tags , , , ,

    Primal heuristics play an important role in the solving of mixed integer programs (MIPs). They often provide good feasible solutions early and help to reduce the time needed to prove optimality. In this paper, we present a scheme for start heuristics that can be executed without previous knowledge of an LP solution or a previously … Read more

    Multi-Objective Optimization for Politically Fair Districting: A Scalable Multilevel Approach

  • Rahul Swamy
  • Douglas King
  • Sheldon Jacobson
    • Categories (Mixed) Integer Linear Programming, Applications - OR and Management Sciences, Multi-Criteria Optimization Tags , , , , , , ,

    Political districting in the United States is a decennial process of redrawing the boundaries of congressional and state legislative districts. The notion of fairness in political districting has been an important topic of subjective debate, with district maps having consequences to multiple stakeholders. Even though districting as an optimization problem has been well-studied, existing models … Read more

    A Decomposition Heuristic for Mixed-Integer Supply Chain Problems

  • Lars Schewe
  • Martin Schmidt
  • Dieter Weninger
    • Categories (Mixed) Integer Linear Programming, Supply Chain Management Tags , , , ,

    Mixed-integer supply chain models typically are very large but are also very sparse and can be decomposed into loosely coupled blocks. In this paper, we use general-purpose techniques to obtain a block decomposition of supply chain instances and apply a tailored penalty alternating direction method, which exploits the structural properties of the decomposed instances. We … Read more

    On the depth of cutting planes

  • Laurent Poirrier
  • James Yu
    • Categories (Mixed) Integer Linear Programming, Branch and Cut Algorithms, Cutting Plane Approaches Tags , ,

    We introduce a natural notion of depth that applies to individual cutting planes as well as entire families. This depth has nice properties that make it easy to work with theoretically, and we argue that it is a good proxy for the practical strength of cutting planes. In particular, we show that its value lies … Read more

    Computing Feasible Points of Bilevel Problems with a Penalty Alternating Direction Method

  • Thomas Kleinert
  • Martin Schmidt
    • Categories (Mixed) Integer Linear Programming, (Mixed) Integer Nonlinear Programming Tags , , , ,

    Bilevel problems are highly challenging optimization problems that appear in many applications of energy market design, critical infrastructure defense, transportation, pricing, etc. Often, these bilevel models are equipped with integer decisions, which makes the problems even harder to solve. Typically, in such a setting in mathematical optimization one develops primal heuristics in order to obtain … Read more

    Avoiding redundant columns by adding classical Benders cuts to column generation subproblems

  • Marco E. Lübbecke
  • Stephen J. Maher
  • Jonas T. Witt
    • Categories (Mixed) Integer Linear Programming Tags , , ,

    When solving the linear programming (LP) relaxation of a mixed-integer program (MIP) with column generation, columns might be generated that are not needed to express any integer optimal solution of the MIP. Such columns are called strongly redundant and the dual bound obtained by solving the LP relaxation is potentially stronger if these columns are … Read more