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We consider the Courier Delivery Problem, a variant of the Vehicle Routing Problem with time windows in which customers appear probabilistically and their service times are uncertain. We use scenario-based stochastic programming with recourse to model the uncertainty in customers and robust optimization for the uncertainty in service times. Our proposed(More)
In this paper we introduce a robust optimization approach to solve the Vehicle Routing Problem (VRP) with demand uncertainty. This approach yields routes that minimize transportation costs while satisfying all demands in a given bounded uncertainty set. We show that for the Miller-Tucker-Zemlin formulation of the VRP and specific uncertainty sets, solving(More)
We study auction-like algorithms for the distributed allocation of tasks to cooperating agents. To reduce the team cost of sequential single-item auction algorithms, we generalize them to assign more than one additional task during each round, which increases their similarity to combinatorial auction algorithms. We show that, for a given number of(More)
It is well known that the Vehicle Routing Problem (VRP) becomes more difficult to solve as the problem size increases. However little is known about what makes a VRP difficult or easy to solve for problems of the same size. In this paper we investigate the effect of the formulation and data parameters on the efficiency with which we can obtain exact(More)
The Vehicle Routing Problem (VRP) is a central problem for many transportation applications, and although it is well known that it is difficult to solve, how much of this difficulty is due to the formulation of the problem is less understood. In this paper we experimentally investigate how the solution times to solve a VRP with a general IP solver are(More)
Twenty-three patients with symptomatic giant hemangioma of the liver were treated by surgery between 1979 and 1996 at the department of General Surgery, Faculty of Medicine, University of Cukurova. Twenty-three enucleations were performed in 21 patients, left lateral segmentectomy in one patient and enucleation plus left lobectomy in one patient. The tumors(More)
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