@inproceedings{BorndoerferKarbsteinMehrgahrdtetal., author = {Bornd{\"o}rfer, Ralf and Karbstein, Marika and Mehrgahrdt, Julika and Reuther, Markus and Schlechte, Thomas}, title = {The Cycle Embedding Problem}, series = {Operations Research Proceedings 2014}, booktitle = {Operations Research Proceedings 2014}, doi = {10.1007/978-3-319-28697-6_65}, pages = {465 -- 472}, abstract = {Given two hypergraphs, representing a fine and a coarse "layer", and a cycle cover of the nodes of the coarse layer, the cycle embedding problem (CEP) asks for an embedding of the coarse cycles into the fine layer. The CEP is NP-hard for general hypergraphs, but it can be solved in polynomial time for graphs. We propose an integer rogramming formulation for the CEP that provides a complete escription of the CEP polytope for the graphical case. The CEP comes up in railway vehicle rotation scheduling. We present computational results for problem instances of DB Fernverkehr AG that justify a sequential coarse-first-fine-second planning approach.}, language = {en} } @article{BorndoerferHoppmannKarbstein, author = {Bornd{\"o}rfer, Ralf and Hoppmann, Heide and Karbstein, Marika}, title = {Passenger routing for periodic timetable optimization}, series = {Public Transport}, journal = {Public Transport}, publisher = {Springer-Verlag Berlin Heidelberg}, doi = {10.1007/s12469-016-0132-0}, abstract = {The task of periodic timetabling is to determine trip arrival and departure times in a public transport system such that travel and transfer times are minimized. This paper investigates periodic timetabling models with integrated passenger routing. We show that different routing models can have a huge influence on the quality of the entire system: Whatever metric is applied, the performance ratios of timetables w.r.t. different routing models can be arbitrarily large. Computations on a real-world instance for the city of Wuppertal substantiate the theoretical findings. These results indicate the existence of untapped optimization potentials that can be used to improve the efficiency of public transport systems by integrating passenger routing.}, language = {en} } @inproceedings{BorndoerferHoppmannKarbstein, author = {Bornd{\"o}rfer, Ralf and Hoppmann, Heide and Karbstein, Marika}, title = {Separation of Cycle Inequalities for the Periodic Timetabling Problem}, series = {24th Annual European Symposium on Algorithms (ESA 2016)}, volume = {57}, booktitle = {24th Annual European Symposium on Algorithms (ESA 2016)}, doi = {10.4230/LIPIcs.ESA.2016.21}, abstract = {Cycle inequalities play an important role in the polyhedral study of the periodic timetabling problem. We give the first pseudo-polynomial time separation algorithm for cycle inequalities, and we give a rigorous proof for the pseudo-polynomial time separability of the change-cycle inequalities. The efficiency of these cutting planes is demonstrated on real-world instances of the periodic timetabling problem.}, language = {en} } @misc{BorndoerferHoppmannKarbsteinetal., author = {Bornd{\"o}rfer, Ralf and Hoppmann, Heide and Karbstein, Marika and L{\"o}bel, Fabian}, title = {The Modulo Network Simplex with Integrated Passenger Routing}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-60319}, abstract = {Periodic timetabling is an important strategic planning problem in public transport. The task is to determine periodic arrival and departure times of the lines in a given network, minimizing the travel time of the passengers. We extend the modulo network simplex method, a well-established heuristic for the periodic timetabling problem, by integrating a passenger (re)routing step into the pivot operations. Computations on real-world networks show that we can indeed find timetables with much shorter total travel time, when we take the passengers' travel paths into consideration.}, language = {en} } @inproceedings{BorndoerferHoppmannKarbsteinetal., author = {Bornd{\"o}rfer, Ralf and Hoppmann, Heide and Karbstein, Marika and L{\"o}bel, Fabian}, title = {The Modulo Network Simplex with Integrated Passenger Routing}, series = {Operations Research Proceedings 2016}, booktitle = {Operations Research Proceedings 2016}, abstract = {Periodic timetabling is an important strategic planning problem in public transport. The task is to determine periodic arrival and departure times of the lines in a given network, minimizing the travel time of the passengers. We extend the modulo network simplex method, a well-established heuristic for the periodic timetabling problem, by integrating a passenger (re)routing step into the pivot operations. Computations on real-world networks show that we can indeed find timetables with much shorter total travel time, when we take the passengers' travel paths into consideration.}, language = {en} }