Timo Gersing

Insights into the computational complexity of the single-source capacitated facility location problem with customer preferences

  • Christina Büsing
  • Timo Gersing
  • Sophia Wrede
    • Categories Combinatorial Optimization Tags , , ,

    Single-source capacitated facility location problems are well studied in the operations research literature, yet classic problems often lack practicability by disregarding the customers’ perspective: An authority that assigns customers to open facilities deprives customers from choosing facilities according to their individual preferences. In reality, this can render solutions infeasible, as customers may deviate to their … Read more

    Minimum-Peak-Cost Flows Over Time

  • Mariia Anapolska
  • Christina Büsing
  • Felix Engelhardt
  • Timo Gersing
  • Sabrina Schmitz
  • Sophia Wrede
    • Categories Combinatorial Optimization, Network Optimization Tags , , , ,

    Peak cost is a novel objective for flows over time that describes the amount of workforce necessary to run a system. We focus on minimising peak costs in the context of maximum temporally repeated flows and formulate the corresponding MPC-MTRF problem. First, we discuss the limitations that emerge when restricting the solution space to integral … 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

    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