Online Optimization of Complex Transportation Systems (2009)
Martin Grötschel, Sven O. Krumke, Jörg Rambau
Abstract This paper discusses online optimization of real-world transportation systems. We concentrate on transportation problems arising in production and manufacturing processes, in particular in...
The Combinatorics of (S,M,L,XL) or the best fitting delivery of T-shirts (2009)
Gaul, Constantin, Kurz, Sascha, Rambau, Jörg
A fashion discounter supplies its branches with apparel in various sizes. Apparel is ordered in pre-packs three months in advance from overseas: replenishment impossible. Thus, the supply in each...
* Combinatorial Online Optimization in Real Time (2008)
Martin Grötschel, Sven O. Krumke, Jörg Rambau, Thomas Winter, T. Zimmermann
Abstract Optimization is Üie task of finding a best solution to a given problem. When the decision variables are discrete we speak of a combinatorial optimization problem. Such a problem is online...
LP-Based Local Approximation for Markov Decision Problems ⋆ (2008)
Stefan Heinz, Volker Kaibel, Matthias Peinhardt, Jörg Rambau, Andreas Tuchscherer, Stefan Heinz, ...
Abstract. The standard computational methods for computing the optimal value functions of Markov Decision Problems (MDP) require the exploration of the entire state space. This is practically...
Sven O. Krumke, Willem E. Paepe, Jörg Rambau, Leen Stougie D
We introduce a new problem that was motivated by a (more complicated) problem arising in a robotized assembly environment. The bin coloring problem is to pack unit size colored items into bins, such...
DEFERMENT CONTROL IN REOPTIMIZATION – HOW TO FIND FAIR REOPTIMIZED DISPATCHES (2008)
ABSTRACT. This note about work in progress suggests new policies for combinatorial online optimization problems where requests have to be served and the longterm objective is a sophisticated...
Computing Triangulations Using Oriented Matroids (2008)
ABSTRACT. Oriented matroids are combinatorial structures that encode the combinatorics of point configurations. The set of all triangulations of a point configuration depends only on its oriented...
Prof Dr, Martin Grötschel, Prof Dr, Jörg Rambau, Stefan Heinz, ...
Although my name is the only one appearing on the title page, several people have been directly and indirectly involved in the creation of this thesis. First of all, I want to thank my supervisors...
Ralf Hülsermann, T-systems Nova, Gmbh Technologiezentrum, Monika Jäger, T-systems Nova, Gmbh Technologiezentrum, ...
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...
Kurz, Sascha, Rambau, Jörg, Schlüchtermann, Jörg, Wolf, Rainer
We propose the new Top-Dog-Index, a measure for the branch-dependent historic deviation of the supply data of apparel sizes from the sales data of a fashion discounter. A common approach is to...
On the benefits of using NP-hard problems in Branch & Bound (2008)
Rambau, Jörg, Schwarz, Cornelius
We present a Brand-and-Bound (B&B) method using combinatorial bounds for solving makespan minimization problems with sequence dependent setup costs. As an application we present a laser source...
Rambau, Jörg, Schwarz, Cornelius, Lehrstuhl Wirtschaftsmathematik
Wir modellieren zwei verschiedene dynamische Einsatzplanungsprobleme: die dynamische Einsatzplanung Gelber Engel beim ADAC und die Steuerung von Lastenaufzügen in einem Versandlager der Herlitz PBS...
Lotsize optimization leading to a p-median problem with cardinalities (2007)
Gaul, Constantin, Kurz, Sascha, Rambau, Jörg
We consider the problem of approximating the branch and size dependent demand of a fashion discounter with many branches by a distributing process being based on the branch delivery restricted to...
We propose the new Top-Dog-Index to quantify the historic deviation of the supply data of many small branches for a commodity group from sales data. On the one hand, the common parametric assumptions...
We develop and experimentally compare policies for the control of a system of k elevators with capacity one in a transport environment with I floors, an idealized version of a pallet elevator system...
Deferment Control for Reoptimization -- How to Find Fair Reoptimized Dispatches (2005)
The german automobile association ADAC maintains a fleet of 1700 vehicles and has agreements with around 5000 service contractors. With these ressources, they help people whose cars have broken down...
How to Cut a Cake Almost Fairly (2002)
Sven O. Krumke, Maarten Lipman, Diana Poensgen, Jörg Rambau, Leen Stougie, ...
In the cake cutting problem, n 2 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...
Real-time dispatching of guided and unguided automobile service units with soft time windows (2002)
Sven O. Krumke, Jörg Rambau, M. Torres
ABSTRACT. We investigate a real-world large scale vehicle dispatching problem with strict real-time requirements, posed by our cooperation partner, the German Automobile Association. We present...
Real-time dispatching of guided and unguided automobile service units with soft time windows (2002)
Luis M. Torres, Sven O. Krumke, Sven O. Krumke, Jörg Rambau, Jörg Rambau, ...
ABSTRACT. Given a set of service requests (events), a set of guided servers (units), and a set of unguided service contractors (conts), the vehicle dispatching problem VDP is the task to find an...
How to cut a cake almost fairly (2002)
Maarten Lipmann Willem, E. De Paepe, Gerhard J. Woeginger, Sven O. Krumke, Sven O. Krumke, Maarten Lipman, ...
ABSTRACT. In the cake cutting problem, n ≥ 2 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 −...
Sven O. Krumke, Willem De Paepe, Jörg Rambau, Leen Stougie
We introduce a new problem that was motivated by a (more complicated) problem arising in a robotized assembly environment. The bin coloring problem is to pack unit size colored items into bins, such...
Combinatorial Online Optimization in Real Time (2001)
Martin Grötschel, Sven O. Krumke, Jörg Rambau, Thomas Winter, Uwe T. Zimmermann
Optimization is the task of finding an optimum solution to a given problem. When the decision variables are discrete we speak of a combinatorial optimization problem. Such a problem is online when...
Sven O. Krumke, Jörg Rambau, Leen Stougie
We introduce a new problem that was motivated by a (more complicated) problem arising in a robotized assembly environment. The bin coloring problem is to pack unit size colored items into bins, such...
Real-Time Dispatching of Guided and Unguided Automobile Service Units with Soft Time Windows (2001)
Sven O. Krumke, Jörg Rambau, Luis M. Torres
We investigate a real-world large scale vehicle dispatching problem with strict real-time requirements, posed by our cooperation partner, the German Automobile Association. We present computational...
Sven O. Krumke, Jörg Rambau, Leen Stougie
ABSTRACT. We introduce a new problem that was motivated by a (more complicated) problem arising in a robotized assembly environment. The bin coloring problem is to pack unit size colored items into...
Online Dial-a-Ride Problems: Minimizing the Completion Time (2000)
Norbert Ascheuer, Sven O. Krumke, Jörg Rambau
. We consider the following online dial-a-ride problem (OlDarp): Objects are to be transported between points in a metric space. Transportation requests arrive online, specifying the objects to be...
The Online Dial-a-Ride Problem under Reasonable Load (2000)
Dietrich Hauptmeier, Sven O. Krumke, Jörg Rambau
. In this paper, we analyze algorithms for the online dial-aride problem with request sets that fulll a certain worst-case restriction: roughly speaking, a set of requests for the online dial-a-ride...
The Online Dial-A-Ride Problem Under Reasonable Load (2000)
Dietrich Hauptmeier, Dietrich Hauptmeier, Sven O. Krumke, Sven O. Krumke, Jörg Rambau, Jörg Rambau
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...
An approximation algorithm for the non-preemptive capacitated dial-a-ride problem (2000)
Sven O. Krumke, Jörg Rambau, Steffen Weider
In the Capacitated Dial-a-Ride Problem (CDARP) we are given a transportation network and a finite set of transportation jobs. Each job specifies the source and target location which are both part of...
The generalized Baues problem for cyclic polytopes II (1999)
Christos A. Athanasiadis, Jörg Rambau, Francisco Santos
Given an affine surjection of polytopes : P! Q, the Generalized Baues Problem asks whether the poset of all proper polyhedral subdivisions of Q which are induced by the map has the homotopy type of a...
Simulation Studies for the Online Dial-a-Ride Problem (1999)
Martin Grötschel, Martin Gr, Otschel Dietrich Hauptmeier, Jörg Rambau, Martin Gr Otschel, Dietrich Hauptmeier, ...
. In a large distribution center of Herlitz AG, Berlin, we investigated the elevator subsystem of the fully automated pallet transportation system. Each elevator may carry one pallet and has to serve...
The Cayley Trick, Lifting Subdivisions And The Bohne-Dress Theorem On Zonotopal Tilings (1999)
Birkett Huber, Jörg Rambau, J Org Rambau, Francisco Santos
. In 1994, Sturmfels gave a polyhedral version of the Cayley Trick of elimination theory: he established an order-preserving bijection between the posets of coherent mixed subdivisions of a Minkowski...
The generalized Baues problem for cyclic polytopes I (1999)
An important special case of the Generalized Baues Problem asks whether the order complex of all proper polyhedral subdivisions of a given point configuration, partially ordered by refinement, is...
Euler is standing in line -- Dial-a-Ride problems with FIFO-precedence-constraints (1999)
Dietrich Hauptmeier, Sven O. Krumke, Jörg Rambau, Hans-Christoph Wirth
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...
Simulation Studies for the Online Dial-a-Ride Problem (1999)
Martin Grötschel, Dietrich Hauptmeier, Sven O. Krumke, Jörg Rambau
In a large distribution center of Herlitz AG, Berlin, we investigated the elevator subsystem of the fully automated pallet transportation system. Each elevator may carry one pallet and has to serve...
The Generalized Baues Problem For Cyclic Polytopes (1998)
. The Generalized Baues Problem asks whether for a given point configuration the order complex of all its proper polyhedral subdivisions, partially ordered by refinement, is homotopy equivalent to a...
The online transportation problem: competitive scheduling of elevators (1998)
Norbert Ascheuer, Sven O. Krumke, Jörg Rambau
In this paper we consider the following online transportation problem (OLTP): Objects are to be transported between the vertices of a given graph. Transportation requests arrive online, specifying...
The Generalized Baues Problem For Cyclic Polytopes II (1998)
Christos A. Athanasiadis, Jörg Rambau, J Org Rambau, Francisco Santos
. Given an affine surjection of polytopes ß : P ! Q, the Generalized Baues Problem asks whether the poset of all proper polyhedral subdivisions of Q which are induced by the map ß has the homotopy...
On Subdivision Posets of Cyclic Polytopes (1997)
Edelman, Paul H., Rambau, Jörg, Reiner, Victor
There are two related poset structures, the higher Stasheff-Tamari orders, on the set of all triangulations of the cyclic $d$ polytope with $n$ vertices. In this paper it is shown that both of them...
A Suspension Lemma for Bounded Posets (1997)
Let $P$ and $Q$ be bounded posets. In this note, a lemma is introduced that provides a set of sufficient conditions for the proper part of $P$ being homotopy equivalent to the suspension of the...
Triangulations of cyclic polytopes and higher Bruhat orders (1997)
Recently EDELMAN & REINER suggested two poset structures S 1 (n;d) and S 2 (n;d) on the set of all triangulations of the cyclic d-polytope C(n;d) with n vertices. Both posets are generalizations...
A Suspension Lemma For Bounded Posets (1997)
Let P and Q be bounded posets. In this note, a lemma is introduced that provides a set of sufficient conditions for the proper part of P being homotopy equivalent to the suspension of the proper part...
Triangulations of Cyclic Polytopes and Higher Bruhat Orders (1997)
Recently EDELMAN & REINER suggested two poset structures S 1 (n;d) and S 2 (n;d) on the set of all triangulations of the cyclic d- polytope C(n;d) with n vertices. Both posets are generalizations...
Projections of Polytopes and the Generalized Baues Conjecture (1996)
Jörg Rambau, Günter M. Ziegler
Associated with every projection ß : P ! ß(P ) of a polytope P one has a partially ordered set of all "locally coherent strings": the families of proper faces of P that project to valid...