@misc{KochMartinVoss2000, author = {Koch, Thorsten and Martin, Alexander and Voß, Stefan}, title = {SteinLib: An Updated Library on Steiner Tree Problems in Graphs}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6056}, number = {00-37}, year = {2000}, abstract = {In this paper we present the {\em SteinLib}, a library of data sets for the Steiner tree problem in graphs. This library extends former libraries on Steiner tree problems by many new interesting and difficult instances, most of them arising from real-world applications. We give a survey on the difficulty of these problem instances by giving references to state-of-the-art software packages that were the first or are currently among the best to solve these instances.}, language = {en} } @misc{BleyKoch2002, author = {Bley, Andreas and Koch, Thorsten}, title = {Integer programming approaches to access and backbone IP-network planning}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7081}, number = {02-41}, year = {2002}, abstract = {In this article we study the problem of designing a nation-wide communication network. Such networks usually consist of an access layer, a backbone layer, and maybe several intermediate layers. The nodes of each layer must be connected to those of the next layer in a tree-like fashion. The backbone layer has to satisfy certain survivability and routing constraints. Given the node locations, the demands between them, the possible connections and hardware configurations, and various other technical and administrational constraints, the goal is to decide, which node is assigned to which network level, how the nodes are connected, what hardware must be installed, and how traffic is routed in the backbone. Mixed integer linear programming models and solution methods are presented for both the access and the backbone network design problem. The focus is on the design of IP-over-SDH networks, but the access network design model and large parts of the backbone network design models are general and also applicable for other types of communication networks. Results obtained with these methods in the planning of the German research network are presented.}, language = {en} } @misc{EisenblaetterFuegenschuhKochetal.2002, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Koch, Thorsten and Koster, Arie M.C.A. and Martin, Alexander and Pfender, Tobias and Wegel, Oliver and Wess{\"a}ly, Roland}, title = {Modelling Feasible Network Configurations for UMTS}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6837}, number = {02-16}, year = {2002}, abstract = {A model for the optimisation of the location and configuration of base stations in a UMTS network is described. The focus is primarily on modelling the configuration problem sufficiently accurate using mixed-integer variables and (essentially) linear constraints. These constraints reflect the limited downlink code capacity in each cell, the interference limitations for successful up- and downlink transmissions, the need for sufficiently strong (cell) pilot signals, and the potential gain for mobiles from being in soft(er) hand-over. It is also explained how to use the model as a basis for rating network configurations.}, language = {en} } @misc{Koch2003, author = {Koch, Thorsten}, title = {The final NETLIB-LP results}, doi = {10.1016/s0167-6377(03)00094-4}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7274}, number = {03-05}, year = {2003}, abstract = {The NETLIB has now served for 18 years as a repository of LP problem instances. From the beginning to the present day there was some uncertainness about the precise values of the optimal solutions. We implemented a program using exact rational arithmetic to compute proofs for the feasibility and optimality of an LP solution. This paper reports the \emph{exact} optimal objective values for all NETLIB problems.}, language = {en} } @misc{AchterbergKochMartin2002, author = {Achterberg, Tobias and Koch, Thorsten and Martin, Alexander}, title = {Branching on History Information}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6990}, number = {02-32}, year = {2002}, abstract = {Mixed integer programs (\$MIPs\$) are commonly solved with branch and bound algorithms based on linear programming. The success and the speed of the algorithm strongly depends on the strategy used to select the branching variables. Today's state-of-the-art strategy is called \emph{pseudocost branching} and uses information of previous branchings to determine the current branching. We propose a modification of \emph{pseudocost branching} which we call \emph{history branching}. This strategy has been implemented in \$SIP\$, a state-of-the-art \$MIP\$ solver. We give computational results that show the superiority of the new strategy.}, language = {en} } @misc{EisenblaetterFuegenschuhGeerdesetal.2003, author = {Eisenbl{\"a}tter, Andreas and F{\"u}genschuh, Armin and Geerdes, Hans-Florian and Junglas, Daniel and Koch, Thorsten and Martin, Alexander}, title = {Optimization Methods for UMTS Radio Network Planning}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7637}, number = {03-41}, year = {2003}, abstract = {The UMTS radio network planning problem poses the challenge of designing a cost-effective network that provides users with sufficient coverage and capacity. We describe an optimization model for this problem that is based on comprehensive planning data of the EU project MOMENTUM. We present heuristic mathematical methods for this realistic model, including computational results.}, language = {en} } @phdthesis{Koch2005, author = {Koch, Thorsten}, title = {Rapid Mathematical Programming}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-8346}, number = {04-58}, year = {2005}, abstract = {The thesis deals with the implementation and application of out-of-the-box tools in linear and mixed integer programming. It documents the lessons learned and conclusions drawn from five years of implementing, maintaining, extending, and using several computer codes to solve real-life industrial problems. By means of several examples it is demonstrated how to apply algebraic modeling languages to rapidly devise mathematical models of real-world problems. It is shown that today's MIP solvers are capable of solving the resulting mixed integer programs, leading to an approach that delivers results very quickly. Even though, problems are tackled that not long ago required the implementation of specialized branch-and-cut algorithms. In the first part of the thesis the modeling language Zimpl is introduced. Chapter 2 contains a complete description of the language. In the subsequent chapter details of the implementation are described. Both theoretical and practical considerations are discussed. Aspects of software engineering, error prevention, and detection are addressed. In the second part several real-world projects are examined that employed the methodology and the tools developed in the first part. Chapter 4 presents three projects from the telecommunication industry dealing with facility location problems. Chapter 5 characterizes questions that arise in UMTS planning. Problems, models, and solutions are discussed. Special emphasis is put on the dependency of the precision of the input data and the results. Possible reasons for unexpected and undesirable solutions are explained. Finally, the Steiner tree packing problem in graphs, a well-known hard combinatorial problem, is revisited. A formerly known, but not yet used model is applied to combine switchbox wire routing and via minimization. All instances known from the literature are solved by this approach, as are some newly generated bigger problem instances.}, language = {en} } @misc{EisenblaetterGeerdesKochetal.2004, author = {Eisenbl{\"a}tter, Andreas and Geerdes, Hans-Florian and Koch, Thorsten and T{\"u}rke, Ulrich}, title = {MOMENTUM Data Scenarios for Radio Network Planning and Simulation (Extended Abstract)}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7829}, number = {04-07}, year = {2004}, abstract = {We present publicly available data sets related to research on wireless networks. The scenarios contain a wide range of data and are detailed in all aspects. To our knowledge, this is the most realistic, comprehensive, and detailed \emph{public} data collection on mobile networking. We indicate example uses of this data collection in applications related tu UMTS.}, language = {en} } @misc{AchterbergKochMartin2004, author = {Achterberg, Tobias and Koch, Thorsten and Martin, Alexander}, title = {Branching rules revisited}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7886}, number = {04-13}, year = {2004}, abstract = {Mixed integer programs are commonly solved with linear programming based branch-and-bound algorithms. The success of the algorithm strongly depends on the strategy used to select the variable to branch on. We present a new generalization called {\sl reliability branching} of today's state-of-the-art {\sl strong branching} and {\sl pseudocost branching} strategies for linear programming based branch-and-bound algorithms. After reviewing commonly used branching strategies and performing extensive computational studies we compare different parameter settings and show the superiority of our proposed newstrategy.}, language = {en} } @misc{EisenblaetterGeerdesKochetal.2004, author = {Eisenbl{\"a}tter, Andreas and Geerdes, Hans-Florian and Koch, Thorsten and Martin, Alexander and Wess{\"a}ly, Roland}, title = {UMTS Radio Network Evaluation and Optimization beyond Snapshots}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7903}, number = {04-15}, year = {2004}, abstract = {This paper is concerned with UMTS radio network design. Our task is to reconfigure antennas and the related cells as to improve network quality. In contrast to second generation GSM networks, \emph{interference} plays a paramount role when designing third generation radio networks. A known compact formulation for assessing the interference characteristics of a radio network as coupling relations between cells based on user snapshots is generalized to statistical average load. This enables us to overcome the notorious difficulties of snapshot-based network optimization approaches. We recall a mixed-integer programming model for the network design problem that is based on user snapshots and contrast it with a new network design model based on the average coupling formulation. Exemplarily focusing on the important problem of optimizing antenna tilts, we give computational results for a fast local search algorithm and the application of a MIP solver to both models. These results demonstrate that our new average-based approaches outperform state-of-the-art snapshot models for UMTS radio network optimization.}, language = {en} } @misc{KochGriebelSoellneretal.2016, author = {Koch, Thorsten and Griebel, Rolf and S{\"o}llner, Konstanze and Christof, J{\"u}rgen and Bertelmann, Roland}, title = {DeepGreen - Entwicklung eines rechtssicheren Workflows zur effizienten Umsetzung der Open-Access-Komponente in den Allianz-Lizenzen f{\"u}r die Wissenschaft}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-56799}, pages = {22}, year = {2016}, abstract = {In Deutschland wurden 2011 wichtige Akzente f{\"u}r die Umsetzung des Gr{\"u}nen Wegs der Open-Access-Bewegung gesetzt: Mit finanzieller Unterst{\"u}tzung der Deutschen Forschungsgemeinschaft (DFG) haben Bibliotheken sogenannte Allianz-Lizenzen mit Verlagen verhandelt, in denen weitreichende Rechte hinsichtlich der Open-Access-Archivierung verankert sind. Autorinnen und Autoren zugriffsberechtigter Einrichtungen k{\"o}nnen ihre Artikel, die in diesen lizenzierten Zeitschriften erschienen sind, ohne oder mit nur kurzer Embargofrist in geeigneten Repositorien ihrer Wahl frei zug{\"a}nglich machen. Allerdings macht der Kreis berechtigter Autorinnen und Autoren nur sehr z{\"o}gerlich von seinen Open-Access-Rechten Gebrauch. Auch die Bibliotheken - als Betreiber der Repositorien und damit Vertreter f{\"u}r die berechtigten Autorinnen und Autoren - nutzen dieses Recht nur unzureichend. Mit DeepGreen verfolgen die Antragssteller das Ziel, einen Großteil jener Publikationen, die unter den speziell im DFG-gef{\"o}rderten Kontext verhandelten Bedingungen gr{\"u}n online gehen d{\"u}rften, auch tats{\"a}chlich online abrufbar zu machen. Im Rahmen des Projektes wird prototypisch mit Allianzverlagen und berechtigten Bibliotheken ein m{\"o}glichst stark automatisierter Workflow entwickelt, in dem rechtssichere Verlagsdaten inklusive der Volltexte abgeliefert und von Repositorien eingespielt werden. Ein technischer Baustein ist dabei ein intermedi{\"a}res Repositorium, das als Datenverteiler dient. Das nationale Projektkonsortium besteht aus den zwei Bibliotheksverb{\"u}nden Kooperativer Bibliotheksverbund Berlin-Brandenburg (KOBV) und Bibliotheksverbund Bayern (BVB), den zwei Universit{\"a}tsbibliotheken der Friedrich-Alexander-Universit{\"a}t Erlangen-N{\"u}rnberg (FAU) und der Technische Universit{\"a}t Berlin (TU Berlin), zus{\"a}tzlich die Bayerische Staatsbibliothek (BSB) und eine außeruniversit{\"a}re Forschungseinrichtung - das Helmholtz Open Science Koordinationsb{\"u}ro am Deutschen GeoForschungsZentrum (GFZ). Das Projekt startet zum 01. Januar 2016. Hier vorliegend finden Sie den Projektantrag zum Nachlesen.}, language = {de} } @misc{Koch2001, author = {Koch, Thorsten}, title = {ZIMPL User Guide}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6466}, number = {01-20}, year = {2001}, abstract = {{\sc Zimpl} is a little language to translate the mathematical model of a problem into a linear or (mixed-)integer mathematical program expressed in {\tt lp} or {\tt mps} file format which can be read by a LP or MIP solver.}, language = {en} } @misc{BleyKoch2000, author = {Bley, Andreas and Koch, Thorsten}, title = {Optimierung in der Planung und beim Aufbau des G-WiN}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6169}, number = {00-48}, year = {2000}, abstract = {Ende Juni diesen Jahres wurde das Gigabit-Wissenschaftsnetz offiziell gestartet. In der zweij{\"a}hrigen Vorbereitungsphase wurden nicht nur die technischen M{\"o}glichkeiten der neuen {\"U}bertragungstechniken und Dienste getestet. Es wurden auch verschiedene Fragestellungen zum effizienten Einsatz der verf{\"u}gbaren Ressourcen f{\"u}r den Betrieb des G-WiN untersucht. In diesem Artikel beschreiben wir, wie das G-WiN zu seiner jetzigen Struktur und Topologie gekommen ist.}, language = {de} } @misc{KaibelKoch2006, author = {Kaibel, Volker and Koch, Thorsten}, title = {Mathematik f{\"u}r den Volkssport}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-9225}, number = {06-28}, year = {2006}, abstract = {"`Volkssport Sudoku"' titelt der Stern in seiner Ausgabe vom 24. Mai2006. In der Tat traut sich derzeit kaum noch eine Zeitung, ohne Sudoku zu erscheinen. Die Begeisterung am L{\"o}sen dieser Zahlenr{\"a}tsel offenbart eine unvermutete Freude am algorithmischen Arbeiten. Mathematisch kann man Sudokus als lineare diophantische Gleichungssysteme mit Nichtnegativit{\"a}tsbedingungen formulieren. Solche ganzzahligen linearen Programme sind die wichtigsten Modellierungswerkzeuge in zahlreichen Anwendungsgebieten wie z.B. der Optimierung von Telekommunikations- und Verkehrsnetzen. Moderne Verfahren zur L{\"o}sung dieser Optimierungsprobleme sind durch Sudokus allerdings deutlich weniger zu beeindrucken als Zeitungsleser.}, language = {de} } @misc{AbboudGroetschelKoch2006, author = {Abboud, Nadine and Gr{\"o}tschel, Martin and Koch, Thorsten}, title = {Mathematical Methods for Physical Layout of Printed Circuit Boards: An Overview}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-9231}, number = {06-29}, year = {2006}, abstract = {This article surveys mathematical models and methods used for physical PCB layout, i.e., component placement and wire routing. The main concepts are briefly described together with relevant references.}, language = {en} } @misc{RuschPetersKottigBoltzeetal.2021, author = {Rusch, Beate and Peters-Kottig, Wolfgang and Boltze, Julia and Brandtner, Andreas and Degkwitz, Andreas and Kirsch, Simona and Koch, Thorsten and Lohrum, Stefan and M{\"u}ller, Anja and Mutter, Moritz and Seeliger, Frank and Stanek, Ursula}, title = {KOBV Jahresbericht 2019-2020}, address = {Berlin}, organization = {Kooperativer Bibliotheksverbund Berlin-Brandenburg}, issn = {1438-0064}, doi = {10.12752/8247}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-82474}, pages = {84}, year = {2021}, abstract = {Der aktuelle KOBV-Jahresbericht informiert dar{\"u}ber, was in den Mitgliedsbibliotheken und Partnerprojekten in den letzten beiden Jahren passiert ist und was sich in der Verbundzentrale und in der Bibliothekslandschaft {\"a}ndert. Die Ausgabe 2019/2020 enth{\"a}lt den Schwerpunktteil »Digitalisierung« mit verschiedenen Perspektiven auf die digitale Arbeitswelt.}, language = {de} } @misc{BertelmannKochCeynowaetal.2022, author = {Bertelmann, Roland and Koch, Thorsten and Ceynowa, Klaus and S{\"o}llner, Konstanze and Christof, J{\"u}rgen and Rusch, Beate and Sch{\"a}ffler, Hildegard and Putnings, Markus and Pampel, Heinz and Kuberek, Monika and Boltze, Julia and Lohrum, Stefan and Retter, Regina and H{\"o}llerl, Annika and Faensen, Katja and Steffen, Ronald and Gross, Matthias and Hoffmann, Cornelia and Haoua, Marsa}, title = {DeepGreen: Etablierung und Weiterentwicklung rechtssicherer Workflows zur effizienten Umsetzung von Open-Access-Komponenten in Lizenzvereinbarungen f{\"u}r wissenschaftliche Publikationen - Abschlussbericht}, issn = {1438-0064}, doi = {10.12752/8542}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-85420}, year = {2022}, abstract = {DeepGreen wurde vom 01.08.2018 bis zum 30.06.2021 in einer zweiten Projektphase von der Deutschen Forschungsgemeinschaft (DFG) gef{\"o}rdert. DeepGreen unterst{\"u}tzt Bibliotheken als Dienstleister f{\"u}r Hochschulen, außeruniversit{\"a}re Forschungseinrichtungen und die dort t{\"a}tigen Wissenschaftler:innen dabei, Publikationen auf Open-Access-Repositorien frei zug{\"a}nglich zu machen und f{\"o}rdert das Zusammenspiel von wissenschaftlichen Einrichtungen und Verlagen. An der zweiten Projektphase waren der Kooperative Bibliotheksverbund Berlin-Brandenburg, die Bayerische Staatsbibliothek, der Bibliotheksverbund Bayern, die Universit{\"a}tsbibliotheken der Friedrich-Alexander-Universit{\"a}t Erlangen-N{\"u}rnberg und der Technischen Universit{\"a}t Berlin und das Helmholtz Open Science Office beteiligt. In dem Projekt wurde erfolgreich eine technische und organisatorische L{\"o}sung zur automatisierten Verteilung von Artikeldaten wissenschaftlicher Verlage an institutionelle und fachliche Repositorien entwickelt. In der zweiten Projektphase lag der Fokus auf der Erprobung der Datendrehscheibe in der Praxis und der Ausweitung auf weitere Datenabnehmer und weitere Verlage. Im Anschluss an die DFG-gef{\"o}rderte Projektlaufzeit ist DeepGreen in einen zweij{\"a}hrigen Pilotbetrieb {\"u}bergegangen. Ziel des Pilotbetriebs ist es, den {\"U}bergang in einen bundesweiten Real-Betrieb vorzubereiten.}, language = {de} } @misc{PetersKottigBrandtnerChristofetal.2023, author = {Peters-Kottig, Wolfgang and Brandtner, Andreas and Christof, J{\"u}rgen and Hauffe, Yves and Koch, Thorsten and Kuo, Leslie and Krause, Katja and M{\"u}ller, Anja and Seeliger, Frank and Stanek, Ursula and St{\"o}hr, Elena and Vetter, Danilo and Winkler, Alexander and Zeyns, Andrea and Rusch, Beate}, title = {KOBV Jahresbericht 2021-2022}, volume = {2021-2022}, address = {Berlin}, organization = {Kooperativer Bibliotheksverbund Berlin-Brandenburg}, issn = {0934-5892}, doi = {10.12752/9116}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-91162}, year = {2023}, language = {de} } @misc{BertelmannBoltzeCeynowaetal.2021, author = {Bertelmann, Roland and Boltze, Julia and Ceynowa, Klaus and Christof, J{\"u}rgen and Faensen, Katja and Groß, Matthias and Hoffmann, Cornelia and Koch, Thorsten and Kuberek, Monika and Lohrum, Stefan and Pampel, Heinz and Putnings, Markus and Retter, Regina and Rusch, Beate and Sch{\"a}ffler, Hildegard and S{\"o}llner, Konstanze and Steffen, Ronald and Wannick, Eike}, title = {DeepGreen: Open-Access-Transformation in der Informationsinfrastruktur - Anforderungen und Empfehlungen, Version 1.0}, issn = {1438-0064}, doi = {10.12752/8150}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-81503}, year = {2021}, abstract = {DeepGreen ist ein Service, der es teilnehmenden institutionellen Open-Access-Repositorien,Open-Access-Fachrepositorien und Forschungsinformationssystemen erleichtert, f{\"u}r sie relevante Verlagspublikationen in zyklischer Abfolge mithilfe von Schnittstellen Open Access zur Verf{\"u}gung zu stellen. Die entsprechende Bandbreite an Relationen zwischen den Akteuren, diverse lizenzrechtliche Rahmenbedingungen sowie technische Anforderungen gestalten das Thema komplex. Ziel dieser Handreichung ist es, neben all diesen Themen, die begleitend beleuchtet werden, im Besonderen Empfehlungen f{\"u}r die reibungslose Nutzung der Daten{\"u}bertragung zu liefern. Außerdem werden mithilfe einer vorangestellten Workflow- Evaluierung Unterschiede und Besonderheiten in den Arbeitsschritten bei institutionellen Open-Access-Repositorien und Open-Access-Fachrepositorien aufgezeigt und ebenfalls mit Empfehlungen angereichert.}, language = {de} } @inproceedings{BreuerBussieckCaoetal.2020, author = {Breuer, Thomas and Bussieck, Michael and Cao, Karl-Kien and Fiand, Fred and Gils, Hans-Christian and Gleixner, Ambros and Khabi, Dmitry and Kempke, Nils and Koch, Thorsten and Rehfeldt, Daniel and Wetzel, Manuel}, title = {BEAM-ME: Accelerating Linear Energy Systems Models by a Massively Parallel Interior Point Method}, volume = {50}, booktitle = {NIC Symposium 2020}, pages = {345 -- 352}, year = {2020}, language = {en} } @article{KochAchterbergAndersenetal.2011, author = {Koch, Thorsten and Achterberg, Tobias and Andersen, Erling and Bastert, Oliver and Berthold, Timo and Bixby, Robert E. and Danna, Emilie and Gamrath, Gerald and Gleixner, Ambros and Heinz, Stefan and Lodi, Andrea and Mittelmann, Hans and Ralphs, Ted and Salvagnin, Domenico and Steffy, Daniel and Wolter, Kati}, title = {MIPLIB 2010}, volume = {3}, journal = {Mathematical Programming Computation}, number = {2}, doi = {10.1007/s12532-011-0025-9}, pages = {103 -- 163}, year = {2011}, language = {en} }