Arie M.C.A. Koster

Professor of Discrete Optimization, RWTH Aachen University, Germany

Integrated Optimization of Timetabling and Electric Vehicle Scheduling: A Case Study of Aachen, Germany

  • Vladimir Stadnichuk
  • Jenny Segschneider
  • Arie M.C.A. Koster
  • Grit Walther
    • Categories Applications - OR and Management Sciences, Approximation Algorithms, Transportation Tags , , , ,

    We tackle the integrated planning problem of periodic timetabling and electric vehicle scheduling, crucial for cities transitioning to electric bus fleets. Given existing timetables, we allow only minor modifications and propose an iterative solution approach that addresses the Electric Vehicle Scheduling Problem (EVSP) in each iteration. Due to the NP-hard nature of EVSP, we employ … Read more

    Complexity of the Directed Robust b-matching Problem and its Variants on Different Graph Classes

  • Jenny Segschneider
  • Arie M.C.A. Koster
    • Categories Network Optimization, Robust Optimization Tags , , ,

    The b-matching problem is a well-known generalization of the classical matching problem with various applications in operations research and computer science. Given an undirected graph, each vertex v has a capacity b(v), indicating the maximum number of times it can be matched, while edges can also be used multiple times. The problem is solvable in … Read more

    Recycling Valid Inequalities for Robust Combinatorial Optimization with Budget Uncertainty

  • Christina Büsing
  • Timo Gersing
  • Arie M.C.A. Koster
    • Categories 0-1 Programming, Polyhedra, Robust Optimization Tags , , , ,

    Robust combinatorial optimization with budget uncertainty is one of the most popular approaches for integrating uncertainty into optimization problems. The existence of a compact reformulation for (mixed-integer) linear programs and positive complexity results give the impression that these problems are relatively easy to solve. However, the practical performance of the reformulation is quite poor when … Read more

    Robust Two-Dose Vaccination Schemes and the Directed b-Matching Problem

  • Jenny Segschneider
  • Arie M.C.A. Koster
    • Categories Applications - OR and Management Sciences, Robust Optimization Tags , , , ,

    In light of the recent pandemic and the shortage of vaccinations during their roll-out, questions arose regarding the best strategy to achieve immunity throughout the population by adjusting the time gap between the two necessary vaccination doses. This strategy has already been studied from different angles by various researches. However, the deliveries of vaccination doses … Read more

    Γ-robust Optimization of Project Scheduling Problems

  • Arie M.C.A. Koster
  • Jenny Segschneider
    • Categories Applications - OR and Management Sciences, Scheduling Tags , , , ,

    \(\) In this paper, we investigate the problem of finding a robust baseline schedule for the project scheduling problem under uncertain process times. We assume that the probability distribution for the duration is unknown but an estimation together with an interval in which this time can vary is given. At most $ \Gamma $ of … Read more

    A Branch & Bound Algorithm for Robust Binary Optimization with Budget Uncertainty

  • Christina Büsing
  • Timo Gersing
  • Arie M.C.A. Koster
    • Categories 0-1 Programming, Branch and Cut Algorithms, Robust Optimization Tags , , , ,

    Since its introduction in the early 2000s, robust optimization with budget uncertainty has received a lot of attention. This is due to the intuitive construction of the uncertainty sets and the existence of a compact robust reformulation for (mixed-integer) linear programs. However, despite its compactness, the reformulation performs poorly when solving robust integer problems due … Read more

    Planning Out-of-Hours Services for Pharmacies

  • Christina Büsing
  • Arie M.C.A. Koster
  • Timo Gersing
    • Categories 0-1 Programming, Applications - OR and Management Sciences, Scheduling Tags , , , , ,

    The supply of pharmaceuticals is one important factor in a functioning health care system. In the German health care system, the chambers of pharmacists are legally obliged to ensure that every resident can find an open pharmacy at any day and night time within an appropriate distance. To that end, the chambers of pharmacists create … Read more

    Improved Handling of Uncertainty and Robustness in Set Covering Problems

  • Christina Büsing
  • Dirk Degel
  • Arie M.C.A. Koster
  • Pascal Lutter
  • Brigitte Werners
    • Categories Applications - OR and Management Sciences, Cutting Plane Approaches, Robust Optimization Tags , , ,

    This paper studies the emergency service facility location problem in an uncertain environment. The main focus is the integration of uncertainty regarding the covered area due to uncertain traveling times. Previous approaches only consider either probabilistic or fuzzy optimization to cope with uncertainty. However, in many real-world problems the required statistical parameters are not precisely … Read more

    DESSLib – Benchmark Instances for Optimization of Decentralized Energy Supply Systems

  • Fritz Arnold
  • Björn Bahl
  • André Bardow
  • Arie M.C.A. Koster
  • Marco E. Lübbecke
  • Sebastian Goderbauer
  • Philip Voll
    • Categories Applications - Science and Engineering Tags , , , , , ,

    DESSLib (http://www.math2.rwth-aachen.de/DESSLib) provides benchmark instances obtained by real world data for synthesis problems of decentralized energy supply systems (DESS). In this paper, the considered optimization problem is described in detail. For a description of the functions and parameters used to describe the system and equipment, see the documentation found on DESSLib website http://www.math2.rwth-aachen.de/DESSLib. Article Download … Read more

    An Adaptive Discretization MINLP Algorithm for Optimal Synthesis of Decentralized Energy Supply Systems

  • Björn Bahl
  • André Bardow
  • Arie M.C.A. Koster
  • Marco E. Lübbecke
  • Sebastian Goderbauer
  • Philip Voll
    • Categories (Mixed) Integer Nonlinear Programming, Applications - Science and Engineering Tags , , , ,

    Decentralized energy supply systems (DESS) are highly integrated and complex systems designed to meet time-varying energy demands, e.g., heating, cooling, and electricity. The synthesis problem of DESS addresses combining various types of energy conversion units, choosing their sizing and operations to maximize an objective function, e.g., the net present value. In practice, investment costs and … Read more