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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)
The airline industry is notably one of the success stories with respect to the use of optimization based methods and tools in planning. Both in planning of the assignment of available aircraft to flights and in crew scheduling, these methods play a major role. Plans are usually made several months prior to the actual day of operation. As a consequence,(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)
Quadratic Assignment problems are in practice among the most diicult to solve in the class of NP-complete problems. The only successful approach hitherto has been Branch-and-Bound-based algorithms, but such algorithms are crucially dependent on good bound functions to limit the size of the space searched. Much work has been done to identify such functions(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 application-independent tasks ensures portability, maintenance, exten-sibility, and flexibility. This paper demonstrates the success in combining problem-specific knowledge for the quadratic(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)
The Aircraft Recovery Problem (ARP) involves decisions concerning aircraft to flight assignments in situations where unforeseen events have disrupted the existing flight schedule, e.g. bad weather causing flight delays. The aircraft recovery problem aims to recover these flight schedules through a series of reassignments of aircraft to flights, delaying of(More)
Program libraries are one tool to make the cooperation between specialists from various elds successful: the separation of application-specic knowledge from application-independent tasks ensures portability, maintenance, extensibility, and exibility. The current paper demonstrates the success in combining problem-speciic knowledge for the quadratic(More)