Learn More
In this paper, we present a constant-factor approximation algorithm for the unsplittable flow problem on a path. This improves on the previous best known approximation factor of O(log n). The approximation ratio of our algorithm is 7+e for any e>0. In the unsplittable flow problem on a path, we are given a capacitated path P and n tasks, each task(More)
We propose a hybrid approach for solving the resource-constrained project scheduling problem which is an extremely hard to solve combinatorial optimization problem of practical relevance. Jobs have to be scheduled on (renewable) resources subject to precedence constraints such that the resource capacities are never exceeded and the latest completion time of(More)
Large-scale maintenance in industrial plants requires the entire shutdown of production units for disassembly, comprehensive inspection and renewal. It is an important process but causes high out-of-service cost. Therefore a good schedule for a shutdown and and an analysis of possible associated risks are crucial for the manufacturer. We derive models and(More)
Energetic reasoning is one of the most powerful propagation algorithms in cumulative scheduling. In practice, however, it is not commonly used because it has a high running time and its success highly depends on the tightness of the variable bounds. In order to speed up energetic reasoning, we provide an easy-to-check necessary condition for energetic(More)
During the last decades, the Internet has steadily developed into a mass medium with millions of users. On the one hand, newfangled services replace traditional ones. Naturally, these are thereby expected to offer at least the same features as their classical pendants, e.g., when VoIP replaces traditional fixed line telephone networks. On the other hand,(More)
During the last years, the Internet has grown into a mass-medium for communication and information exchange. Millions of people are using the Internet for business and in social life. Users can be reached easily and cost-effectively. Unfortunately the Internet's open structure is the reason for its frequent misuse for illegal and criminal actions such as(More)
Dual presolving reductions are a class of reformulation techniques that remove feasible or even optimal solutions while guaranteeing that at least one optimal solution remains, as long as the original problem was feasible. Presolving and dual reductions are important components of state-of-the-art mixed-integer linear programming solvers. In this paper, we(More)
Resource leveling is a variant of resource-constrained project scheduling in which a non-regular objective function, the resource availability cost, is to be minimized. We present a branch-and-price approach together with a new heuristic to solve the more general turnaround scheduling problem. Besides precedence and resource constraints, also availability(More)
Predicting vehicles' behaviors in a traffic scene can be very challenging due to many influences. Especially interactions with other traffic participants like vehicles or pedestrians are very crucial for the future movement while they are hard to model even with expert knowledge. In this paper we propose an object-oriented probabilistic approach that(More)