Integer Programming

Risk-aware Logic-based Benders Decomposition for a Location-Allocation-Pricing Problem with Stochastic Price-Sensitive Demands

  • Maryam Daryalal
  • Ahmadi-Javid Amir
    • Categories (Mixed) Integer Linear Programming, Facility Planning and Design, Stochastic Programming Tags , ,

    We consider a capacitated location-allocation-pricing problem in a single-commodity supply chain with stochastic price-sensitive demands, where the location, allocation and pricing decisions are made simultaneously. Under a general risk measure representing an arbitrary risk tolerance policy, the problem is modeled as a two-stage stochastic mixed-integer program with a translation-invariant monotone risk measure. To solve the … Read more

    Analyzing the numerical correctness of branch-and-bound decisions for mixed-integer programming

  • Alexander Hoen
  • Ambros Gleixner
    • Categories (Mixed) Integer Linear Programming, Integer Programming Tags , ,

    Most state-of-the-art branch-and-bound solvers for mixed-integer linear programming rely on limited-precision floating-point arithmetic and use numerical tolerances when reasoning about feasibility and optimality during their search. While the practical success of floating-point MIP solvers bears witness to their overall numerical robustness, it is well-known that numerically challenging input can lead them to produce incorrect results. … Read more

    Multi-Stage Selection under Bounded Variation

  • Christoph Buchheim
  • Maja Hügging
    • Categories 0-1 Programming, Dynamic Programming Tags , , , ,

    We investigate a multi-stage version of the selection problem where the variation between solutions in consecutive stages is either penalized in the objective function or bounded by hard constraints. While the former problem turns out to be tractable, the complexity of the latter problem depends on the type of bounds imposed: When bounding the number … Read more

    A Two-stage Stochastic Programming Approach for CRNA Scheduling with Handovers

  • Ankit Bansal
  • Osman Y. Ozaltin
    • Categories (Mixed) Integer Linear Programming, Scheduling, Stochastic Programming Tags , , ,

    We present a two-stage stochastic integer program for assigning Certified Registered Nurse Anesthetists (CRNAs) to Operating Rooms (ORs) under surgery duration uncertainty. The proposed model captures the trade-offs between CRNA staffing levels, CRNA handovers and under-staffing in the ORs. Since the stochastic program includes binary variables in both stages, we present valid inequalities to tighten … Read more

    MIP-DD: Delta Debugging for Mixed Integer Programming Solvers

  • Alexander Hoen
  • Dominik Kamp
  • Ambros Gleixner
    • Categories (Mixed) Integer Linear Programming, Integer Programming Tags ,

    The recent performance improvements in mixed-integer programming (MIP) have been accompanied by a significantly increased complexity of the codes of MIP solvers, which poses challenges in fixing implementation errors. In this paper, we introduce MIP-DD, a solver-independent tool, which to the best of our knowledge is the first open-source delta debugger for MIP. Delta debugging … Read more

    Integrated Schedule Planning for Regional Airlines Using Column Generation

  • Alberto Santini
    • Categories (Mixed) Integer Linear Programming, Airline Optimization, Combinatorial Optimization Tags , , , ,

    Problem definition: More than one-third of US domestic flights are operated by regional airlines. This paper focuses on optimizing medium-term schedule planning decisions for a network of regional airlines through the joint optimization of frequency planning, timetable development, fleet assignment, and some limited aspects of route planning, while capturing passengers’ travel decisions through a general … Read more

    An Oracle-based Approach for Price-setting Problems in Logistics

  • Nele Pommerening
  • Maja Hügging
  • Dorothee Henke
  • Christoph Buchheim
  • Uwe Clausen
    • Categories Integer Programming, Transportation Tags , , ,

    We study a bilevel hub location problem where on the upper level, a shipment service provider –the leader–builds a transportation network and sets the prices of shipments on each possible transportation relation. Here, the leader has to take into account the customers’ reaction — the follower — who will only purchase transport services depending on … Read more

    Pessimistic bilevel optimization approach for decision-focused learning

  • Diego Jiménez
  • Bernardo K. Pagnoncelli
  • Hande Yaman
    • Categories 0-1 Programming, Stochastic Programming Tags , ,

    The recent interest in contextual optimization problems, where randomness is associated with side information, has led to two primary strategies for formulation and solution. The first, estimate-then-optimize, separates the estimation of the problem’s parameters from the optimization process. The second, decision-focused optimization, integrates the optimization problem’s structure directly into the prediction procedure. In this work, … Read more

    Strengthening Dual Bounds for Multicommodity Capacitated Network Design with Unsplittable Flow Constraints

  • Lacy M. Greening
  • Santanu S. Dey
  • Alan L. Erera
    • Categories Integer Programming, Network Optimization, Production and Logistics Tags , , ,

    Multicommodity capacitated network design (MCND) models can be used to optimize the consolidation of shipments within e-commerce fulfillment networks. In practice, fulfillment networks require that shipments with the same origin and destination follow the same transfer path. This unsplittable flow requirement complicates the MCND problem, requiring integer programming (IP) formulations with binary variables replacing continuous … Read more

    Lagrangian Duality for Mixed-Integer Semidefinite Programming: Theory and Algorithms

  • Frank de Meijer
  • Renata Sotirov
    • Categories (Mixed) Integer Nonlinear Programming, Semi-definite Programming Tags , , ,

    This paper presents the Lagrangian duality theory for mixed-integer semidefinite programming (MISDP). We derive the Lagrangian dual problem and prove that the resulting Lagrangian dual bound dominates the bound obtained from the continuous relaxation of the MISDP problem. We present a hierarchy of Lagrangian dual bounds by exploiting the theory of integer positive semidefinite matrices … Read more