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DOI: 10.4230/OASIcs.ATMOS.2012.71

On the Complexity of Partitioning Graphs for Arc-Flags

Authors: Reinhard Bauer, Moritz Baum, Ignaz Rutter, and Dorothea Wagner

Published in: OASIcs, Volume 25, 12th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2012)

Abstract

Precomputation of auxiliary data in an additional off-line step is a common approach towards improving the performance of shortest-path queries in large-scale networks. One such technique is the arc-flags algorithm, where the preprocessing involves computing a partition of the input graph. The quality of this partition significantly affects the speed-up observed in the query phase. It is evaluated by considering the search-space size of subsequent shortest-path queries, in particular its maximum or its average over all queries. In this paper, we substantially strengthen existing hardness results of Bauer et al. and show that optimally filling this degree of freedom is NP-hard for trees with unit-length edges, even if we bound the height or the degree. On the other hand, we show that optimal partitions for paths can be computed efficiently and give approximation algorithms for cycles and trees.

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Reinhard Bauer, Moritz Baum, Ignaz Rutter, and Dorothea Wagner. On the Complexity of Partitioning Graphs for Arc-Flags. In 12th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 25, pp. 71-82, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)

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@InProceedings{bauer_et_al:OASIcs.ATMOS.2012.71,
  author =	{Bauer, Reinhard and Baum, Moritz and Rutter, Ignaz and Wagner, Dorothea},
  title =	{{On the Complexity of Partitioning Graphs for Arc-Flags}},
  booktitle =	{12th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{71--82},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-45-3},
  ISSN =	{2190-6807},
  year =	{2012},
  volume =	{25},
  editor =	{Delling, Daniel and Liberti, Leo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2012.71},
  URN =		{urn:nbn:de:0030-drops-37048},
  doi =		{10.4230/OASIcs.ATMOS.2012.71},
  annote =	{Keywords: shortest paths, arc-flags, search space, preprocessing, complexity}
}

Document

DOI: 10.4230/OASIcs.ATMOS.2007.1169

14. Experimental Study on Speed-Up Techniques for Timetable Information Systems

Authors: Reinhard Bauer, Daniel Delling, and Dorothea Wagner

Published in: OASIcs, Volume 7, 7th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS'07) (2007)

Abstract

During the last years, impressive speed-up techniques for Dijkstra's algorithm have been developed. Unfortunately, recent research mainly focused on road networks. However, fast algorithms are also needed for other applications like timetable information systems. Even worse, the adaption of recently developed techniques to timetable information is often more complicated than expected. In this work, we check whether results from road networks are transferable to timetable information. To this end, we present an extensive experimental study of the most prominent speed-up techniques on different types of inputs. It turns out that recently developed techniques are much slower on graphs derived from timetable information than on road networks. In addition, we gain amazing insights into the behavior of speed-up techniques in general.

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Reinhard Bauer, Daniel Delling, and Dorothea Wagner. 14. Experimental Study on Speed-Up Techniques for Timetable Information Systems. In 7th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS'07). Open Access Series in Informatics (OASIcs), Volume 7, pp. 209-225, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{bauer_et_al:OASIcs.ATMOS.2007.1169,
  author =	{Bauer, Reinhard and Delling, Daniel and Wagner, Dorothea},
  title =	{{14. Experimental Study on Speed-Up Techniques for Timetable Information Systems}},
  booktitle =	{7th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS'07)},
  pages =	{209--225},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-04-0},
  ISSN =	{2190-6807},
  year =	{2007},
  volume =	{7},
  editor =	{Ahuja, Ravindra K. and Liebchen, Christian and Mesa, Juan A.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2007.1169},
  URN =		{urn:nbn:de:0030-drops-11695},
  doi =		{10.4230/OASIcs.ATMOS.2007.1169},
  annote =	{Keywords: Speed-up techniques, timetable information, shortest path}
}

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Documents authored by Bauer, Reinhard

On the Complexity of Partitioning Graphs for Arc-Flags

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14. Experimental Study on Speed-Up Techniques for Timetable Information Systems

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