@misc{BorndoerferEgererKarbsteinetal.2018, author = {Bornd{\"o}rfer, Ralf and Egerer, Ascan and Karbstein, Marika and Messerschmidt, Ralf and Perez, Marc and Pfisterer, Steven and Strauß, Petra}, title = {Kombil{\"o}sung: Optimierung des Liniennetzes in Karlsruhe}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-69677}, year = {2018}, abstract = {Wir beschreiben die Optimierung des Nahverkehrsnetzes der Stadt Karlsruhe im Zusammmenhang mit den Baumaßnahmen der sogenannten Kombil{\"o}sung.}, language = {de} } @misc{PfetschBorndoerfer2005, author = {Pfetsch, Marc and Bornd{\"o}rfer, Ralf}, title = {Routing in Line Planning for Public Transportation}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-8706}, number = {05-36}, year = {2005}, abstract = {The line planning problem is one of the fundamental problems in strategic planning of public and rail transport. It consists in finding lines and corresponding frequencies in a network such that a giv en demand can be satisfied. There are two objectives. Passengers want to minimize travel times, the transport company wishes to minimize operating costs. We investigate three variants of a multi-commo dity flow model for line planning that differ with respect to passenger routings. The first model allows arbitrary routings, the second only unsplittable routings, and the third only shortest path rou tings with respect to the network. We compare these models theoretically and computationally on data for the city of Potsdam.}, language = {en} } @misc{BorndoerferGroetschelPfetsch2005, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Pfetsch, Marc}, title = {A Column-Generation Approach to Line Planning in Public Transport}, doi = {/10.1287/trsc.1060.0161}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-8522}, number = {05-18}, year = {2005}, abstract = {The line planning problem is one of the fundamental problems in strategic planning of public and rail transport. It consists in finding lines and corresponding frequencies in a transport network such that a given travel demand can be satisfied. There are (at least) two objectives. The transport company wishes to minimize operating costs, the passengers want to minimize travel times. We propose a n ew multi-commodity flow model for line planning. Its main features, in comparison to existing models, are that the passenger paths can be freely routed and that the lines are generated dynamically. We discuss properties of this model and investigate its complexity. Results with data for the city of Potsdam, Germany, are reported.}, language = {en} } @misc{BorndoerferGroetschelPfetsch2005, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Pfetsch, Marc}, title = {Public Transport to the fORe!}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-8562}, number = {05-22}, year = {2005}, abstract = {Can OR methods help the public transport industry to break even? The article gives evidence that there exist significant potentials in this direction, which can be harnessed by a combination of modern mathematical methods and local planning knowledge. Many of the planning steps in public transport are classical combinatorial problems, which can be solved in unprecedented size and quality due the rapid progress in large-scale optimization. Three examples on vehicle scheduling, duty scheduling, and integrated vehicle and duty scheduling illustrate the level that has been reached and the improvements that can be achieved today. Extensions of such methods to further questions of strategic, online, and market-oriented planning are currently investigated. In this way, OR can make a significant contribution to answer the basic but extremely difficult question ``What is a good public transport network?.}, language = {en} } @misc{BorndoerferGroetschelLoebel2000, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and L{\"o}bel, Andreas}, title = {Der schnellste Weg zum Ziel}, journal = {Alles Mathematik}, editor = {Aigner, Martin and Behrends, Ehrhard}, publisher = {Vieweg Verlag}, address = {Braunschweig/Wiesbaden}, doi = {10.1007/978-3-322-96366-6_5}, pages = {45 -- 76}, year = {2000}, language = {en} } @incollection{BorndoerferGroetschelJaeger2008, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Jaeger, Ulrich}, title = {Planungsprobleme im {\"o}ffentlichen Verkehr}, booktitle = {PRODUKTIONSFAKTOR MATHEMATIK - Wie Mathematik Technik und Wirtschaft bewegt}, editor = {Gr{\"o}tschel, Martin and Lucas, Klaus and Mehrmann, Volker}, publisher = {acatech - Deutsche Akademie der Technikwissenschaften und Springer}, pages = {127 -- 153}, year = {2008}, language = {en} } @inproceedings{BorndoerferGroetschelPfetsch2008, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Pfetsch, Marc}, title = {Models for Line Planning in Public Transport}, volume = {600}, booktitle = {Computer-aided Systems in Public Transport (CASPT 2004)}, editor = {Hickman, Mark and Mirchandani, Pitu and Voß, Stefan}, publisher = {Springer-Verlag}, doi = {10.1007/978-3-540-73312-6_18}, pages = {363 -- 378}, year = {2008}, language = {en} } @article{BorndoerferGroetschelPfetsch2007, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Pfetsch, Marc}, title = {A Column-Generation Approach to Line Planning in Public Transport}, volume = {41}, journal = {Transportation Science (INFORMS)}, number = {1}, doi = {10.1287/trsc.1060.0161}, pages = {123 -- 132}, year = {2007}, language = {en} } @misc{BorndoerferFerreiraMartin1997, author = {Bornd{\"o}rfer, Ralf and Ferreira, Carlos E. and Martin, Alexander}, title = {Matrix Decomposition by Branch-and-Cut}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-2839}, number = {SC-97-14}, year = {1997}, abstract = {In this paper we investigate whether matrices arising from linear or integer programming problems can be decomposed into so-called {\em bordered block diagonal form}. More precisely, given some matrix \$A\$, we try to assign as many rows as possible to some number of blocks of limited size such that no two rows assigned to different blocks intersect in a common column. Bordered block diagonal form is desirable because it can guide and speed up the solution process for linear and integer programming problems. We show that various matrices from the \%LP- and MIP-libraries \Netlib{} and MIPLIB can indeed be decomposed into this form by computing optimal decompositions or decompositions with proven quality. These computations are done with a branch-and-cut algorithm based on polyhedral investigations of the matrix decomposition problem.}, language = {en} } @misc{BorndoerferGroetschelHerzogetal.1996, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Herzog, Werner and Klostermeier, Fridolin and Konsek, Wilhelm and K{\"u}ttner, Christian}, title = {K{\"u}rzen muß nicht Kahlschlag heißen - das Beispiel Telebus-Behindertenfahrdienst Berlin}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-2510}, number = {SC-96-41}, year = {1996}, abstract = {M{\"u}ssen Etatk{\"u}rzungen bei staatlichen Dienstleistungseinrichtungen notwendig zu Leistungseinschr{\"a}nkungen oder Geb{\"u}hrenerh{\"o}hungen f{\"u}hren? Wir zeigen am Beispiel des Berliner Behindertenfahrdienstes {\em Telebus}, da\ss{} Sparzwang auch als Chance zur Verbesserung der eigenen Verwaltungs- und Arbeitsabl{\"a}ufe genutzt werden kann. Durch st{\"a}rkere Dienstleistungsorientierung, Vereinfachung der Arbeitsabl{\"a}ufe und durch den Einsatz von moderner EDV und von mathematischen Optimierungsmethoden zur Fahrzeugeinsatzplanung werden bei Telebus heute staatliche Leistungen trotz geringeren Etats besser erbracht als vorher.}, language = {de} } @misc{BorndoerferGroetschelKlostermeieretal.1996, author = {Bornd{\"o}rfer, Ralf and Gr{\"o}tschel, Martin and Klostermeier, Fridolin and K{\"u}ttner, Christian}, title = {Telebus Berlin - Mobilit{\"a}t f{\"u}r Behinderte}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-2500}, number = {SC-96-40}, year = {1996}, abstract = {Steigendes Mobilit{\"a}tsbed{\"u}rfnis der Behinderten bei angespannter Haushaltslage --- diese Situation ergab vor drei Jahren beim Berliner Behindertenfahrdienst {\em Telebus\/} Handlungsbedarf. Gleichzeitig stie\ss{} die verwendete manuelle (Fahrzeug-)Tourenplanung mit damals etwa 1.000 Fahrtw{\"u}nschen pro Tag an ihre Grenzen. Zur L{\"o}sung dieser Probleme war der effiziente Einsatz von Computern und von {\em mathematischen Optimierungsverfahren\/} erforderlich. Ergebnis des daraufhin gestarteten {\em Telebus-Projektes\/} ist die Entwicklung eines neuen, alle Arbeitsabl{\"a}ufe unterst{\"u}tzenden Computersystems, das seit {\"u}ber einem Jahr im Einsatz ist. Herzst{\"u}ck dieses Systems ist ein auf mathematischen Methoden der ganzzahligen Optimierung basierendes Verfahren zur Tourenplanung. Ziel dieses Artikels ist die Beschreibung dieses Verfahrens und seiner Verwendung bei der Behindertenbef{\"o}rderung. Das Beispiel Telebus zeigt, da\ss{} der Einsatz mathematischer Optimierungstechniken neue M{\"o}glichkeiten f{\"u}r Kosteneinsparungen bei gleichzeitiger Serviceverbesserung auch in anderen Bereichen des {\"O}PNV er{\"o}ffnet.}, language = {de} } @misc{AbdelHamidBorndoerfer1994, author = {Abdel-Hamid, Atef Abdel-Aziz and Bornd{\"o}rfer, Ralf}, title = {On the Complexity of Storage Assignment Problems.}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-1430}, number = {SC-94-14}, year = {1994}, abstract = {{\def\NP{\hbox{\$\cal N\kern-.1667em\cal P\$}} The {\sl storage assignment problem} asks for the cost minimal assignment of containers with different sizes to storage locations with different capacities. Such problems arise, for instance, in the optimal control of automatic storage devices in flexible manufacturing systems. This problem is known to be \$\NP\$-hard in the strong sense. We show that the storage assignment problem is \$\NP\$-hard for {\sl bounded sizes and capacities}, even if the sizes have values \$1\$ and~\$2\$ and the capacities value~\$2\$ only, a case we encountered in practice. Moreover, we prove that no polynomial time \$\epsilon\$-approximation algorithm exists. This means that almost all storage assignment problems arising in practice are indeed hard.}}, language = {en} }