4 Search Results for "Kliewer, Natalia"

Document
DOI: 10.4230/LIPIcs.SEA.2024.3
Practical Minimum Path Cover

Authors: Manuel Cáceres, Brendan Mumey, Santeri Toivonen, and Alexandru I. Tomescu

Published in: LIPIcs, Volume 301, 22nd International Symposium on Experimental Algorithms (SEA 2024)

Abstract
Computing a minimum path cover (MPC) of a directed acyclic graph (DAG) is a fundamental problem with a myriad of applications, including reachability. Although it is known how to solve the problem by a simple reduction to minimum flow, recent theoretical advances exploit this idea to obtain algorithms parameterized by the number of paths of an MPC, known as the width. These results obtain fast [Mäkinen et al., TALG 2019] and even linear time [Cáceres et al., SODA 2022] algorithms in the small-width regime. In this paper, we present the first publicly available high-performance implementation of state-of-the-art MPC algorithms, including the parameterized approaches. Our experiments on random DAGs show that parameterized algorithms are orders-of-magnitude faster on dense graphs. Additionally, we present new fast pre-processing heuristics based on transitive edge sparsification. We show that our heuristics improve MPC-solvers by orders of magnitude.
Cite as

Manuel Cáceres, Brendan Mumey, Santeri Toivonen, and Alexandru I. Tomescu. Practical Minimum Path Cover. In 22nd International Symposium on Experimental Algorithms (SEA 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 301, pp. 3:1-3:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

Copy BibTex To Clipboard

@InProceedings{caceres_et_al:LIPIcs.SEA.2024.3,
  author =	{C\'{a}ceres, Manuel and Mumey, Brendan and Toivonen, Santeri and Tomescu, Alexandru I.},
  title =	{{Practical Minimum Path Cover}},
  booktitle =	{22nd International Symposium on Experimental Algorithms (SEA 2024)},
  pages =	{3:1--3:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-325-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{301},
  editor =	{Liberti, Leo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2024.3},
  URN =		{urn:nbn:de:0030-drops-203687},
  doi =		{10.4230/LIPIcs.SEA.2024.3},
  annote =	{Keywords: minimum path cover, directed acyclic graph, maximum flow, parameterized algorithms, edge sparsification, algorithm engineering}
}
Document
DOI: 10.4230/LIPIcs.SEA.2024.15
Determining Fixed-Length Paths in Directed and Undirected Edge-Weighted Graphs

Authors: Daniel Hambly, Rhyd Lewis, and Padraig Corcoran

Published in: LIPIcs, Volume 301, 22nd International Symposium on Experimental Algorithms (SEA 2024)

Abstract
In this paper, we examine the NP-hard problem of identifying fixed-length s-t paths in edge-weighted graphs - that is, a path of a desired length k from a source vertex s to a target vertex t. Many existing strategies look at paths whose lengths are determined by the number of edges in the path. We, however, look at the length of the path as the sum of the edge weights. Here, three exact algorithms for this problem are proposed: the first based on an integer programming (IP) formulation, the second a backtracking algorithm, and the third based on an extension of Yen’s algorithm. Analysis of these algorithms on random graphs shows that the backtracking algorithm performs best on smaller values of k, whilst the IP is preferable for larger values of k.
Cite as

Daniel Hambly, Rhyd Lewis, and Padraig Corcoran. Determining Fixed-Length Paths in Directed and Undirected Edge-Weighted Graphs. In 22nd International Symposium on Experimental Algorithms (SEA 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 301, pp. 15:1-15:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

Copy BibTex To Clipboard

@InProceedings{hambly_et_al:LIPIcs.SEA.2024.15,
  author =	{Hambly, Daniel and Lewis, Rhyd and Corcoran, Padraig},
  title =	{{Determining Fixed-Length Paths in Directed and Undirected Edge-Weighted Graphs}},
  booktitle =	{22nd International Symposium on Experimental Algorithms (SEA 2024)},
  pages =	{15:1--15:11},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-325-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{301},
  editor =	{Liberti, Leo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2024.15},
  URN =		{urn:nbn:de:0030-drops-203805},
  doi =		{10.4230/LIPIcs.SEA.2024.15},
  annote =	{Keywords: Graphs, paths, backtracking, integer programming, Yen’s algorithm}
}
Document
DOI: 10.4230/DagSemProc.09261.12
Increasing Stability of Crew Schedules in Airlines

Authors: Leena Suhl, Viktor Dück, and Natalia Kliewer

Published in: Dagstuhl Seminar Proceedings, Volume 9261, Models and Algorithms for Optimization in Logistics (2009)

Abstract
In airline traffic disruptions occur frequently and cannot be totally avoided. They may lead to infeasible aircraft and crew schedules during the day of operations, due to absence of resources or violation of crew rules. The process of finding new schedules in such cases is called recovery or disruption management. The short-term recovery actions usually imply additional costs meaning that the total operational costs of a crew schedule can be significantly higher than the original planned costs. It is generally desirable to construct the schedule already in the planning phase in such a way that not just the planned costs, but the total operational costs are minimized. The goal is thus to construct schedules which remain feasible or can be recovered without high costs in cases of disturbances. This approach is generally called robust scheduling.
Cite as

Leena Suhl, Viktor Dück, and Natalia Kliewer. Increasing Stability of Crew Schedules in Airlines. In Models and Algorithms for Optimization in Logistics. Dagstuhl Seminar Proceedings, Volume 9261, pp. 1-3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

Copy BibTex To Clipboard

@InProceedings{suhl_et_al:DagSemProc.09261.12,
  author =	{Suhl, Leena and D\"{u}ck, Viktor and Kliewer, Natalia},
  title =	{{Increasing Stability of Crew Schedules in Airlines}},
  booktitle =	{Models and Algorithms for Optimization in Logistics},
  pages =	{1--3},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{9261},
  editor =	{Cynthia Barnhart and Uwe Clausen and Ulrich Lauther and Rolf H. M\"{o}hring},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.09261.12},
  URN =		{urn:nbn:de:0030-drops-21786},
  doi =		{10.4230/DagSemProc.09261.12},
  annote =	{Keywords: Robust planning, crew scheduling, airlines}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2007.1167
08. Branching Strategies to Improve Regularity of Crew Schedules in Ex-Urban Public Transit

Authors: Ingmar Steinzen, Leena Suhl, and Natalia Kliewer

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

Abstract
We discuss timetables in ex-urban bus traffic that consist of many trips serviced every day together with some exceptions that do not repeat daily. Traditional optimization methods for vehicle and crew scheduling in such cases usually produce schedules that contain irregularities which are not desirable especially from the point of view of the bus drivers. We propose a solution method which improves regularity while partially integrating the vehicle and crew scheduling problems. The approach includes two phases: first we solve the LP relaxation of a set partitioning formulation, using column generation together with Lagrangean relaxation techniques. In a second phase we generate integer solutions using a new combination of local branching and various versions of follow-on branching. Numerical tests with artificial and real instances show that regularity can be improved significantly with no or just a minor increase of costs.
Cite as

Ingmar Steinzen, Leena Suhl, and Natalia Kliewer. 08. Branching Strategies to Improve Regularity of Crew Schedules in Ex-Urban Public Transit. In 7th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS'07). Open Access Series in Informatics (OASIcs), Volume 7, pp. 107-123, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

Copy BibTex To Clipboard

@InProceedings{steinzen_et_al:OASIcs.ATMOS.2007.1167,
  author =	{Steinzen, Ingmar and Suhl, Leena and Kliewer, Natalia},
  title =	{{08. Branching Strategies to Improve Regularity of Crew Schedules in Ex-Urban Public Transit}},
  booktitle =	{7th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS'07)},
  pages =	{107--123},
  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.2007.1167},
  URN =		{urn:nbn:de:0030-drops-11674},
  doi =		{10.4230/OASIcs.ATMOS.2007.1167},
  annote =	{Keywords: }
}
  • Refine by Author
  • 2 Kliewer, Natalia
  • 2 Suhl, Leena
  • 1 Corcoran, Padraig
  • 1 Cáceres, Manuel
  • 1 Dück, Viktor
  • Show More...

  • Refine by Classification
  • 1 Information systems → Fixed length attributes
  • 1 Theory of computation → Backtracking
  • 1 Theory of computation → Graph algorithms analysis
  • 1 Theory of computation → Integer programming
  • 1 Theory of computation → Network flows

  • Refine by Keyword
  • 1 Graphs
  • 1 Robust planning
  • 1 Yen’s algorithm
  • 1 airlines
  • 1 algorithm engineering
  • Show More...

  • Refine by Type
  • 4 document

  • Refine by Publication Year
  • 2 2024
  • 1 2007
  • 1 2009

Questions / Remarks / Feedback
X

Feedback for Dagstuhl Publishing


Thanks for your feedback!

Feedback submitted

Could not send message

Please try again later or send an E-mail
© 2023-2024 Schloss Dagstuhl – LZI GmbH Imprint Privacy Contact