Jens Clausen

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An exact solution method for the graph bisection problem is presented. We describe a branch-and-bound algorithm which is based on a cutting plane approach combining semideenite programming and polyhedral relax-ations. We report on extensive numerical experiments which were performed for various classes of graphs. The results indicate that the present(More)
A large number of real-world planning problems called combinatorial optimization problems share the following properties: They are optimization problems, are easy to state, and have a finite but usually very large number of feasible solutions. While some of these as e.g. the Shortest Path problem and the Minimum Spanning Tree problem have polynomial(More)
Program libraries are one tool to make the cooperation between specialists from various elds successful: the separation of application-speci c knowledge from applicationindependent tasks ensures portability, maintenance, extensibility, and exibility. The current paper demonstrates the success in combining problem-speci c knowledge for the quadratic(More)
This paper deals with disruption management in passenger railway transportation. In the disruption management process, many actors belonging to different organizations play a role. In this paper we therefore describe the process itself and the roles of the different actors. Furthermore, we discuss the three main subproblems in railway disruption management:(More)
Over the past decade, cross-docking has emerged as an important material handling technology in transportation. A variation of the well-known Vehicle Routing Problem (VRP), the Vehicle Routing Problem with Cross-Docking (VRPCD) arises in a number of logistics planning contexts. This paper addresses the VRPCD, where a set of homogeneous vehicles are used to(More)
The Best-First Search strategy (BeFS) and the Depth-First Search strategy (DFS) are regarded as the prime strategies when solving combinatorial optimization problems by parallel Branch-and-Bound (B&B) – BeFS because of efficiency with respect to the number of nodes explored, and DFS for reasons of space efficiency. We investigate the efficiency of both(More)
In this paper, we consider the Manpower Allocation Problem with Time Windows, Job-Teaming Constraints and a limited number of teams (m-MAPTWTC). Given a set of teams and a set of tasks, the problem is to assign to each team a sequential order of tasks to maximize the total number of assigned tasks. Both teams and tasks may be restricted by time windows(More)
Program libraries are one way to make the cooperation between specialists from various fields successful: the separation of application-specific knowledge from applicationindependent tasks ensures portability, maintenance, extensibility, and flexibility. This paper demonstrates the success in combining problem-specific knowledge for the quadratic assignment(More)