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Documents authored by Coene, Sofie


Document
The Lockmaster's problem

Authors: Sofie Coene and Frits C. R. Spieksma

Published in: OASIcs, Volume 20, 11th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2011)


Abstract
Inland waterways form a natural network that is an existing, congestion free infrastructure with capacity for more traffic. The European commission promotes the transportation of goods by ship as it is a reliable, efficient and environmental friendly way of transport. A bottleneck for transportation over water are the locks that manage the water level. The lockmaster's problem concerns the optimal strategy for operating such a lock. In the lockmaster's problem we are given a lock, a set of ships coming from downstream that want to go upstream, and another set of ships coming from upstream that want to go downstream. We are given the arrival times of the ships and a constant lockage time; the goal is to minimize total waiting time of the ships. In this paper a dynamic programming algorithm (DP) is proposed that solves the lockmaster's problem in polynomial time. We extend this DP to different generalizations that consider weights, water usage, capacity, and (a fixed number of) multiple chambers. Finally, we prove that the problem becomes strongly NP-hard when the number of chambers is part of the input.

Cite as

Sofie Coene and Frits C. R. Spieksma. The Lockmaster's problem. In 11th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 20, pp. 27-37, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{coene_et_al:OASIcs.ATMOS.2011.27,
  author =	{Coene, Sofie and Spieksma, Frits C. R.},
  title =	{{The Lockmaster's problem}},
  booktitle =	{11th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{27--37},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-33-0},
  ISSN =	{2190-6807},
  year =	{2011},
  volume =	{20},
  editor =	{Caprara, Alberto and Kontogiannis, Spyros},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2011.27},
  URN =		{urn:nbn:de:0030-drops-32647},
  doi =		{10.4230/OASIcs.ATMOS.2011.27},
  annote =	{Keywords: lock scheduling, batch scheduling, dynamic programming, complexity}
}
Document
Heuristics for the Traveling Repairman Problem with Profits

Authors: Thijs Dewilde, Dirk Cattrysse, Sofie Coene, Frits C. R. Spieksma, and Pieter Vansteenwegen

Published in: OASIcs, Volume 14, 10th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS'10) (2010)


Abstract
In the traveling repairman problem with profits, a repairman (also known as the server) visits a subset of nodes in order to collect time-dependent profits. The objective consists of maximizing the total collected revenue. We restrict our study to the case of a single server with nodes located in the Euclidean plane. We investigate properties of this problem, and we derive a mathematical model assuming that the number of visited nodes is known in advance. We describe a tabu search algorithm with multiple neighborhoods, and we test its performance by running it on instances based on TSPLIB. We conclude that the tabu search algorithm finds good-quality solutions fast, even for large instances.

Cite as

Thijs Dewilde, Dirk Cattrysse, Sofie Coene, Frits C. R. Spieksma, and Pieter Vansteenwegen. Heuristics for the Traveling Repairman Problem with Profits. In 10th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS'10). Open Access Series in Informatics (OASIcs), Volume 14, pp. 34-44, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)


Copy BibTex To Clipboard

@InProceedings{dewilde_et_al:OASIcs.ATMOS.2010.34,
  author =	{Dewilde, Thijs and Cattrysse, Dirk and Coene, Sofie and Spieksma, Frits C. R. and Vansteenwegen, Pieter},
  title =	{{Heuristics for the Traveling Repairman Problem with Profits}},
  booktitle =	{10th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS'10)},
  pages =	{34--44},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-20-0},
  ISSN =	{2190-6807},
  year =	{2010},
  volume =	{14},
  editor =	{Erlebach, Thomas and L\"{u}bbecke, Marco},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2010.34},
  URN =		{urn:nbn:de:0030-drops-27489},
  doi =		{10.4230/OASIcs.ATMOS.2010.34},
  annote =	{Keywords: Traveling Repairman, Profits, Latency, Tabu Search, Relief Efforts}
}
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