@incollection{GroetschelKrumkeRambau2001, author = {Gr{\"o}tschel, Martin and Krumke, Sven and Rambau, J{\"o}rg}, title = {Online Optimization of Complex Transportation Systems}, booktitle = {Online Optimization of Large Scale Systems}, editor = {Gr{\"o}tschel, Martin and Krumke, Sven and Rambau, J{\"o}rg}, publisher = {Springer}, pages = {705 -- 729}, year = {2001}, language = {en} } @misc{KrumkeRambauTorres2002, author = {Krumke, Sven and Rambau, J{\"o}rg and Torres, Luis Miguel}, title = {Online-Dispatching of Automobile Service Units}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7117}, number = {02-44}, year = {2002}, abstract = {We present an online algorithm for a real-world vehicle dispatching problem at ADAC, the German Automobile Association.}, language = {en} } @misc{HuelsermannJaegerKrumkeetal.2002, author = {H{\"u}lsermann, Ralf and J{\"a}ger, Monika and Krumke, Sven and Poensgen, Diana and Rambau, J{\"o}rg and Tuchscherer, Andreas}, title = {Dynamic Routing Algorithms in Transparent Optical Networks An Experimental Study Based on Real Data}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7025}, number = {02-35}, year = {2002}, abstract = {Today's telecommunication networks are configured statically. Whenever a connection is established, the customer has permanent access to it. However, it is observed that usually the connection is not used continuously. At this point, dynamic provisioning could increase the utilization of network resources. WDM based Optical Transport Networks (OTNs) will shortly allow for fast dynamic network reconfiguration. This enables optical broadband leased line services on demand. Since service requests competing for network resources may lead to service blocking, it is vital to use appropriate strategies for routing and wavelength assignment in transparent optical networks. We simulate the service blocking probabilities of various dynamic algorithms for this problem using a well-founded traffic model for two realistic networks. One of the algorithms using shortest path routings performs best on all instances. Surprisingly, the tie-breaking rule between equally short paths in different wavelengths decides between success or failure.}, language = {en} } @misc{Rambau2002, author = {Rambau, J{\"o}rg}, title = {TOPCOM: Triangulations of Point Configurations and Oriented Matroids}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6849}, number = {02-17}, year = {2002}, abstract = {TOPCOM is a package for computing triangulations of point configurations and oriented matroids. For example, for a point configuration one can compute the chirotope, components of the flip graph of triangulations, enumerate all triangulations. The core algorithms implemented in TOPCOM are described, and implentation issues are discussed.}, language = {en} } @misc{GroetschelKrumkeRambauetal.2002, author = {Gr{\"o}tschel, Martin and Krumke, Sven and Rambau, J{\"o}rg and Torres, Luis Miguel}, title = {Making the Yellow Angels Fly: Online Dispatching Of Service Vehicles in Real Time}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6858}, number = {02-18}, year = {2002}, abstract = {Combinatorial online optimization is an area with lots of applications and potential for significant progress, both in theory and practice. In this short note we sketch the ADACproblem, a typical large-scale online optimization problem, discuss some theoretical and pratical issues coming up, and explain, very briefly, how we approach this problem mathematically. Online problems are a battlefield of heuristics with many strong claims about their solution quality. We indicate that a stronger problem orientation and the use of a little more mathematics may yield.}, language = {en} } @misc{KrumkeLipmannPaepeetal.2002, author = {Krumke, Sven and Lipmann, Maarten and Paepe, Willem de and Poensgen, Diana and Rambau, J{\"o}rg and Stougie, Leen and Woeginger, Gerhard}, title = {How to Cut a Cake Almost Fairly}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6905}, number = {02-23}, year = {2002}, abstract = {In the cake cutting problem, \$n\ge2\$ players want to cut a cake into \$n\$ pieces so that every player gets a ``fair'' share of the cake by his own measure. We describe a protocol with \$n-1\$~cuts in which each player can enforce to get a share of at least~\$1/(2n-2)\$. Moreover we show that no protocol with \$n-1\$~cuts can guarantee a better fraction.}, language = {en} } @misc{GroetschelKrumkeRambau1999, author = {Gr{\"o}tschel, Martin and Krumke, Sven and Rambau, J{\"o}rg}, title = {Wo bleibt der Aufzug?}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-4175}, number = {SC-99-29}, year = {1999}, abstract = {Dieser Artikel gibt eine allgemeinverst{\"a}ndliche Einf{\"u}hrung in die spezielle Problematik kombinatorischer Online-Problem am Beispiel der Fahrstuhlsteuerung.}, language = {de} } @misc{HauptmeierKrumkeRambauetal.1999, author = {Hauptmeier, Dietrich and Krumke, Sven and Rambau, J{\"o}rg and Wirth., Hans-Christoph}, title = {Euler is Standing in Line}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-3947}, number = {SC-99-06}, year = {1999}, abstract = {In this paper we study algorithms for ``Dial-a-Ride'' transportation problems. In the basic version of the problem we are given transportation jobs between the vertices of a graph and the goal is to find a shortest transportation that serves all the jobs. This problem is known to be NP-hard even on trees. We consider the extension when precedence relations between the jobs with the same source are given. Our results include a polynomial time algorithm on paths and an approximation algorithm on general graphs with a performance of~\$9/4\$. For trees we improve the performance to~\$5/3\$.}, language = {en} } @misc{HauptmeierKrumkeRambau1999, author = {Hauptmeier, Dietrich and Krumke, Sven and Rambau, J{\"o}rg}, title = {The Online Dial-a-Ride Problem under Reasonable Load}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-3961}, number = {SC-99-08}, year = {1999}, abstract = {In this paper, we analyze algorithms for the online dial-a-ride problem with request sets that fulfill a certain worst-case restriction: roughly speaking, a set of requests for the online dial-a-ride problem is reasonable if the requests that come up in a sufficiently large time period can be served in a time period of at most the same length. This new notion is a stability criterion implying that the system is not overloaded. The new concept is used to analyze the online dial-a-ride problem for the minimization of the maximal resp.\ average flow time. Under reasonable load it is possible to distinguish the performance of two particular algorithms for this problem, which seems to be impossible by means of classical competitive analysis.}, language = {en} } @misc{GroetschelHauptmeierKrumkeetal.1999, author = {Gr{\"o}tschel, Martin and Hauptmeier, Dietrich and Krumke, Sven and Rambau, J{\"o}rg}, title = {Simulation Studies for the Online-Dial-a-Ride Problem}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-3976}, number = {SC-99-09}, year = {1999}, abstract = {In a large distribution center of Herlitz AG, Berlin, we invesigated the elevator subsystem of the fully automated pallet transportation system. Each elevator may carry one pallet and has to serve eight levels. The goal is to minimize the average resp.\ the maximum flow time. The variants of this elevator control problem have been subject of recent theoretical research and are known as online-dial-a-ride problems. In this paper we investigate several online algorithms for several versions of online-dial-a-ride problems by means of a simulation program, developed on the basis of the simulation library AMSEL. We draw statistics from samples of randomly generated data providing for different load situations. Moreover, we provide preliminary studies with real production data for a system of five elevators connected by a conveyor circuit, as can be found at the Herlitz plant. We show which algorithms are best under certain load situations and which lead to break downs under particular circumstances.}, language = {en} }