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We present a number of improvements of the basic variant of the arc-flag acceleration (Lauther, 1997, 2004) for point-to-point (P2P) shortest path computations on large graphs. Arc-flags are a modification to the standard Dijkstra algorithm and are used to avoid exploring unnecessary paths during shortest path computation. We assume that for the same input(More)
We consider the problem to minimize the total weighted completion time of a set of jobs with individual release dates which have to be scheduled on identical parallel machines. Job processing times are not known in advance, they are realized on-line according to given probability distributions. The aim is to find a scheduling policy that minimizes the(More)
This paper deals with methods for solving resource-constrained project-scheduling problems. Among the project activities there can be resource conflicts due to the finite capacity of the resources. The paper aims at describing a new method for minimizing the expected makespan while all the possible resource conflicts get eliminated. The novelty of the(More)
We present a new concept for optimization under uncertainty: recoverable robustness. A solution is recovery robust if it can be recovered by limited means in all likely scenarios. Specializing the general concept to linear programming we can show that recoverable robustness combines the flexibility of stochastic programming with the tractability and(More)
PREFACE After having received my diploma from the Technische Universität Berlin in 1996, Rolf Möhring, the supervisor of my diploma thesis, offered me a research position in his group. At that time I was employed at a Berlin software company the head of which, Gert Scheschonk, strongly encouraged me to accept the offer. I accepted and in 1997 I began to(More)
In many scheduling applications it is required that the processing of some job be postponed until some other job, which can be chosen from a pregiven set of alternatives, has been completed. The traditional concept of precedence constraints fails to model such restrictions. Therefore , the concept has been generalized to so-called and/or precedence(More)