31 Search Results for "Lindner, Niels"


Volume

OASIcs, Volume 106

22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)

ATMOS 2022, September 8-9, 2022, Potsdam, Germany

Editors: Mattia D'Emidio and Niels Lindner

Document
Using A* for Optimal Train Routing on Moving Block Systems

Authors: Stefan Engels and Robert Wille

Published in: OASIcs, Volume 137, 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)


Abstract
Modern control systems based on Moving Block allow for shorter headways and higher capacity on existing railway infrastructure. At the same time, few algorithms for optimal routing on networks equipped with such modern control systems exist. Previous methods rely on Mixed Integer Linear Programming (MILP) and face a trade-off between model size and accuracy, especially considering comparably complex and nonlinear headway constraints as well as train dynamics. With this work, we propose a complementary approach based on A*. Under a reasonable and easy assumption on train driver behavior, we propose a solution encoding and state space that is flexible concerning the choice of search algorithm and the modeling detail. The applicability is showcased on a small benchmark set. The implementation is available open-source as part of the Munich Train Control Toolkit (MTCT) on GitHub at https://github.com/cda-tum/mtct.

Cite as

Stefan Engels and Robert Wille. Using A* for Optimal Train Routing on Moving Block Systems. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 14:1-14:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{engels_et_al:OASIcs.ATMOS.2025.14,
  author =	{Engels, Stefan and Wille, Robert},
  title =	{{Using A* for Optimal Train Routing on Moving Block Systems}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{14:1--14:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-404-8},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{137},
  editor =	{Sauer, Jonas and Schmidt, Marie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2025.14},
  URN =		{urn:nbn:de:0030-drops-247701},
  doi =		{10.4230/OASIcs.ATMOS.2025.14},
  annote =	{Keywords: ETCS, Train Routing, Moving Block, A*, Munich Train Control Toolkit}
}
Document
The Fair Periodic Assignment Problem

Authors: Rolf Nelson van Lieshout and Bartholomeüs Theodorus Cornelis van Rossum

Published in: OASIcs, Volume 137, 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)


Abstract
We study the periodic assignment problem, in which a set of periodically repeating tasks must be assigned to workers within a repeating schedule. The classical efficiency objective is to minimize the number of workers required to operate the schedule. We propose a 𝒪(n log n) algorithm to solve this problem. Next, we formalize a notion of fairness among workers, and impose that each worker performs the same work over time. We analyze the resulting trade-off between efficiency and fairness, showing that the price of fairness is at most one extra worker, and that such a fair solution can always be found using the Nearest Neighbor heuristic. We characterize all instances that admit a solution that is both fair and efficient, and use this result to develop a 𝒪(n log n) exact algorithm for the fair periodic assignment problem. Finally, we show that allowing aperiodic schedules never reduces the price of fairness.

Cite as

Rolf Nelson van Lieshout and Bartholomeüs Theodorus Cornelis van Rossum. The Fair Periodic Assignment Problem. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 1:1-1:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{vanlieshout_et_al:OASIcs.ATMOS.2025.1,
  author =	{van Lieshout, Rolf Nelson and van Rossum, Bartholome\"{u}s Theodorus Cornelis},
  title =	{{The Fair Periodic Assignment Problem}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{1:1--1:16},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-404-8},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{137},
  editor =	{Sauer, Jonas and Schmidt, Marie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2025.1},
  URN =		{urn:nbn:de:0030-drops-247574},
  doi =		{10.4230/OASIcs.ATMOS.2025.1},
  annote =	{Keywords: Cyclic scheduling, Fairness, Traveling Salesman Problem}
}
Document
A Geometric Approach to Integrated Periodic Timetabling and Passenger Routing

Authors: Fabian Löbel and Niels Lindner

Published in: OASIcs, Volume 137, 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)


Abstract
We offer a geometric perspective on the problem of integrated periodic timetabling and passenger routing in public transport. Inside the space of periodic tensions, we single out those regions, where the same set of paths provides shortest passenger routes. This results in a polyhedral subdivision, which we combine with the known decomposition by polytropes. On each maximal region of the common refinement, the integrated problem is solvable in polynomial time. We transform these insights into a new geometry-driven primal heuristic, integrated tropical neighborhood search (ITNS). Computationally, we compare implementations of ITNS and the integrated (restricted) modulo network simplex algorithm on the TimPassLib benchmark set, and contribute better solutions in terms of total travel time for all but one of the twenty-five instances for which a proven optimal solution is not yet known.

Cite as

Fabian Löbel and Niels Lindner. A Geometric Approach to Integrated Periodic Timetabling and Passenger Routing. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 2:1-2:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{lobel_et_al:OASIcs.ATMOS.2025.2,
  author =	{L\"{o}bel, Fabian and Lindner, Niels},
  title =	{{A Geometric Approach to Integrated Periodic Timetabling and Passenger Routing}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{2:1--2:19},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-404-8},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{137},
  editor =	{Sauer, Jonas and Schmidt, Marie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2025.2},
  URN =		{urn:nbn:de:0030-drops-247580},
  doi =		{10.4230/OASIcs.ATMOS.2025.2},
  annote =	{Keywords: Periodic Timetabling, Passenger Routing, Polyhedral Complexes}
}
Document
Directed Temporal Tree Realization for Periodic Public Transport: Easy and Hard Cases

Authors: Julia Meusel, Matthias Müller-Hannemann, and Klaus Reinhardt

Published in: OASIcs, Volume 137, 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)


Abstract
We study the complexity of the directed periodic temporal graph realization problem. This work is motivated by the design of periodic schedules in public transport with constraints on the quality of service. Namely, we require that the fastest path between (important) pairs of vertices is upper bounded by a specified maximum duration, encoded in an upper distance matrix D. While previous work has considered the undirected version of the problem, the application in public transport schedule design requires the flexibility to assign different departure times to the two directions of an edge. A problem instance can only be feasible if all values of the distance matrix are at least shortest path distances. However, the task of realizing exact fastest path distances in a periodic temporal graph is often too restrictive. Therefore, we introduce a minimum slack parameter k that describes a lower bound on the maximum allowed waiting time on each path. We concentrate on tree topologies and provide a full characterization of the complexity landscape with respect to the period Δ and the minimum slack parameter k, showing a sharp threshold between NP-complete cases and cases which are always realizable. We also provide hardness results for the special case of period Δ = 2 for general directed and undirected graphs.

Cite as

Julia Meusel, Matthias Müller-Hannemann, and Klaus Reinhardt. Directed Temporal Tree Realization for Periodic Public Transport: Easy and Hard Cases. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 3:1-3:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{meusel_et_al:OASIcs.ATMOS.2025.3,
  author =	{Meusel, Julia and M\"{u}ller-Hannemann, Matthias and Reinhardt, Klaus},
  title =	{{Directed Temporal Tree Realization for Periodic Public Transport: Easy and Hard Cases}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{3:1--3:22},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-404-8},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{137},
  editor =	{Sauer, Jonas and Schmidt, Marie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2025.3},
  URN =		{urn:nbn:de:0030-drops-247594},
  doi =		{10.4230/OASIcs.ATMOS.2025.3},
  annote =	{Keywords: Periodic timetabling, service quality, temporal graph, graph realization, complexity}
}
Document
Periodic Event Scheduling with Flexible Infrastructure Assignment

Authors: Enrico Bortoletto, Rolf Nelson van Lieshout, Berenike Masing, and Niels Lindner

Published in: OASIcs, Volume 123, 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)


Abstract
We present novel extensions of the Periodic Event Scheduling Problem (PESP) that integrate the assignment of activities to infrastructure elements. An application of this is railway timetabling, as station and platform capacities are limited and need to be taken into account. We show that an assignment of activities to platforms can always be made periodic, and that it can be beneficial to allow larger periods for the assignment than for the timetable. We present mixed-integer programming formulations for the general problem, as well as for the practically relevant case when multiple platforms can be considered equivalent, for which we present a bipartite matching approach. We finally test and compare these models on real-world instances.

Cite as

Enrico Bortoletto, Rolf Nelson van Lieshout, Berenike Masing, and Niels Lindner. Periodic Event Scheduling with Flexible Infrastructure Assignment. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 4:1-4:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{bortoletto_et_al:OASIcs.ATMOS.2024.4,
  author =	{Bortoletto, Enrico and van Lieshout, Rolf Nelson and Masing, Berenike and Lindner, Niels},
  title =	{{Periodic Event Scheduling with Flexible Infrastructure Assignment}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{4:1--4:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-350-8},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{123},
  editor =	{Bouman, Paul C. and Kontogiannis, Spyros C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2024.4},
  URN =		{urn:nbn:de:0030-drops-211929},
  doi =		{10.4230/OASIcs.ATMOS.2024.4},
  annote =	{Keywords: Periodic Event Scheduling, Periodic Timetabling, Railway Timetabling, Matchings, Infrastructure Assignments, Platform Assignments, Station Capacities}
}
Document
Periodic Timetabling: Travel Time vs. Regenerative Energy

Authors: Sven Jäger, Sarah Roth, and Anita Schöbel

Published in: OASIcs, Volume 123, 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)


Abstract
While it is important to provide attractive public transportation to the passengers allowing short travel times, it should also be a major concern to reduce the amount of energy used by the public transport system. Electrical trains can regenerate energy when braking, which can be used by a nearby accelerating train. Therefore, apart from the minimization of travel times, the maximization of brake-traction overlaps of nearby trains is an important objective in periodic timetabling. Recently, this has been studied in a model allowing small modifications of a nominal timetable. We investigate the problem of finding periodic timetables that are globally good in both objective functions. We show that the general problem is NP-hard, even restricted to a single transfer station and if only travel time is to be minimized, and give an algorithm with an additive error bound for maximizing the brake-traction overlap on this small network. Moreover, we identify special cases in which the problem is solvable in polynomial time. Finally, we demonstrate the trade-off between the two objective functions in an experimental study.

Cite as

Sven Jäger, Sarah Roth, and Anita Schöbel. Periodic Timetabling: Travel Time vs. Regenerative Energy. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 10:1-10:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{jager_et_al:OASIcs.ATMOS.2024.10,
  author =	{J\"{a}ger, Sven and Roth, Sarah and Sch\"{o}bel, Anita},
  title =	{{Periodic Timetabling: Travel Time vs. Regenerative Energy}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{10:1--10:20},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-350-8},
  ISSN =	{2190-6807},
  year =	{2024},
  volume =	{123},
  editor =	{Bouman, Paul C. and Kontogiannis, Spyros C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2024.10},
  URN =		{urn:nbn:de:0030-drops-211983},
  doi =		{10.4230/OASIcs.ATMOS.2024.10},
  annote =	{Keywords: periodic timetabling, regenerative braking}
}
Document
Integrating Line Planning for Construction Sites into Periodic Timetabling via Track Choice

Authors: Berenike Masing, Niels Lindner, and Christian Liebchen

Published in: OASIcs, Volume 115, 23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023)


Abstract
We consider maintenance sites for urban rail systems, where unavailable tracks typically require changes to the regular timetable, and often even to the line plan. In this paper, we present an integrated mixed-integer linear optimization model to compute an optimal line plan that makes best use of the available tracks, together with a periodic timetable, including its detailed routing on the tracks within the stations. The key component is a flexible, turn-sensitive event-activity network that allows to integrate line planning and train routing using a track choice extension of the Periodic Event Scheduling Problem (PESP). Major goals are to maintain as much of the regular service as possible, and to keep the necessary changes rather local. Moreover, we present computational results on real construction site scenarios on the S-Bahn Berlin network. We demonstrate that this integrated problem is indeed solvable on practically relevant instances.

Cite as

Berenike Masing, Niels Lindner, and Christian Liebchen. Integrating Line Planning for Construction Sites into Periodic Timetabling via Track Choice. In 23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023). Open Access Series in Informatics (OASIcs), Volume 115, pp. 5:1-5:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{masing_et_al:OASIcs.ATMOS.2023.5,
  author =	{Masing, Berenike and Lindner, Niels and Liebchen, Christian},
  title =	{{Integrating Line Planning for Construction Sites into Periodic Timetabling via Track Choice}},
  booktitle =	{23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023)},
  pages =	{5:1--5:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-302-7},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{115},
  editor =	{Frigioni, Daniele and Schiewe, Philine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2023.5},
  URN =		{urn:nbn:de:0030-drops-187669},
  doi =		{10.4230/OASIcs.ATMOS.2023.5},
  annote =	{Keywords: Periodic Timetabling, Line Planning, Track Choice, Mixed-Integer Programming, Construction Sites, Railway Rescheduling}
}
Document
Periodic Timetabling with Cyclic Order Constraints

Authors: Enrico Bortoletto, Niels Lindner, and Berenike Masing

Published in: OASIcs, Volume 115, 23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023)


Abstract
Periodic timetabling for highly utilized railway networks is a demanding challenge. We formulate an infrastructure-aware extension of the Periodic Event Scheduling Problem (PESP) by requiring that not only events, but also activities using the same infrastructure must be separated by a minimum headway time. This extended problem can be modeled as a mixed-integer program by adding constraints on the sum of periodic tensions along certain cycles, so that it shares some structural properties with standard PESP. We further refine this problem by fixing cyclic orders at each infrastructure element. Although the computational complexity remains unchanged, the mixed-integer programming model then becomes much smaller. Furthermore, we also discuss how to find a minimal subset of infrastructure elements whose cyclic order already prescribes the order for the remaining parts of the network, and how cyclic order information can be modeled in a mixed-integer programming context. In practice, we evaluate the impact of cyclic orders on a real-world instance on the S-Bahn Berlin network, which turns out to be computationally fruitful.

Cite as

Enrico Bortoletto, Niels Lindner, and Berenike Masing. Periodic Timetabling with Cyclic Order Constraints. In 23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023). Open Access Series in Informatics (OASIcs), Volume 115, pp. 7:1-7:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{bortoletto_et_al:OASIcs.ATMOS.2023.7,
  author =	{Bortoletto, Enrico and Lindner, Niels and Masing, Berenike},
  title =	{{Periodic Timetabling with Cyclic Order Constraints}},
  booktitle =	{23rd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2023)},
  pages =	{7:1--7:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-302-7},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{115},
  editor =	{Frigioni, Daniele and Schiewe, Philine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2023.7},
  URN =		{urn:nbn:de:0030-drops-187689},
  doi =		{10.4230/OASIcs.ATMOS.2023.7},
  annote =	{Keywords: Periodic Timetabling, Railway Timetabling, Periodic Event Scheduling Problem, Cyclic Orders, Mixed-Integer Programming}
}
Document
Complete Volume
OASIcs, Volume 106, ATMOS 2022, Complete Volume

Authors: Mattia D'Emidio and Niels Lindner

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
OASIcs, Volume 106, ATMOS 2022, Complete Volume

Cite as

22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 1-240, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@Proceedings{demidio_et_al:OASIcs.ATMOS.2022,
  title =	{{OASIcs, Volume 106, ATMOS 2022, Complete Volume}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{1--240},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022},
  URN =		{urn:nbn:de:0030-drops-171036},
  doi =		{10.4230/OASIcs.ATMOS.2022},
  annote =	{Keywords: OASIcs, Volume 106, ATMOS 2022, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Mattia D'Emidio and Niels Lindner

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
Front Matter, Table of Contents, Preface, Conference Organization

Cite as

22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 0:i-0:x, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{demidio_et_al:OASIcs.ATMOS.2022.0,
  author =	{D'Emidio, Mattia and Lindner, Niels},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{0:i--0:x},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022.0},
  URN =		{urn:nbn:de:0030-drops-171040},
  doi =		{10.4230/OASIcs.ATMOS.2022.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
An A* Algorithm for Flight Planning Based on Idealized Vertical Profiles

Authors: Marco Blanco, Ralf Borndörfer, and Pedro Maristany de las Casas

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
The Flight Planning Problem is to find a minimum fuel trajectory between two airports in a 3D airway network under consideration of the wind. We show that this problem is NP-hard, even in its most basic version. We then present a novel A* heuristic, whose potential function is derived from an idealized vertical profile over the remaining flight distance. This potential is, under rather general assumptions, both admissible and consistent and it can be computed efficiently. The method outperforms the state-of-the-art heuristic on real-life instances.

Cite as

Marco Blanco, Ralf Borndörfer, and Pedro Maristany de las Casas. An A* Algorithm for Flight Planning Based on Idealized Vertical Profiles. In 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 1:1-1:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{blanco_et_al:OASIcs.ATMOS.2022.1,
  author =	{Blanco, Marco and Bornd\"{o}rfer, Ralf and Maristany de las Casas, Pedro},
  title =	{{An A* Algorithm for Flight Planning Based on Idealized Vertical Profiles}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{1:1--1:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022.1},
  URN =		{urn:nbn:de:0030-drops-171052},
  doi =		{10.4230/OASIcs.ATMOS.2022.1},
  annote =	{Keywords: shortest path problem, a-star algorithm, flight trajectory optimization, flight planning, heuristics}
}
Document
A Discrete-Continuous Algorithm for Globally Optimal Free Flight Trajectory Optimization

Authors: Ralf Borndörfer, Fabian Danecker, and Martin Weiser

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
We present an efficient algorithm that finds a globally optimal solution to the 2D Free Flight Trajectory Optimization Problem (aka Zermelo Navigation Problem) up to arbitrary precision in finite time. The algorithm combines a discrete and a continuous optimization phase. In the discrete phase, a set of candidate paths that densely covers the trajectory space is created on a directed auxiliary graph. Then Yen’s algorithm provides a promising set of discrete candidate paths which subsequently undergo a locally convergent refinement stage. Provided that the auxiliary graph is sufficiently dense, the method finds a path that lies within the convex domain around the global minimizer. From this starting point, the second stage will converge rapidly to the optimum. The density of the auxiliary graph depends solely on the wind field, and not on the accuracy of the solution, such that the method inherits the superior asymptotic convergence properties of the optimal control stage.

Cite as

Ralf Borndörfer, Fabian Danecker, and Martin Weiser. A Discrete-Continuous Algorithm for Globally Optimal Free Flight Trajectory Optimization. In 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 2:1-2:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


Copy BibTex To Clipboard

@InProceedings{borndorfer_et_al:OASIcs.ATMOS.2022.2,
  author =	{Bornd\"{o}rfer, Ralf and Danecker, Fabian and Weiser, Martin},
  title =	{{A Discrete-Continuous Algorithm for Globally Optimal Free Flight Trajectory Optimization}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{2:1--2:13},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022.2},
  URN =		{urn:nbn:de:0030-drops-171068},
  doi =		{10.4230/OASIcs.ATMOS.2022.2},
  annote =	{Keywords: shortest path, flight planning, free flight, discretization error bounds, optimal control, discrete optimization, global optimization}
}
Document
Tropical Neighbourhood Search: A New Heuristic for Periodic Timetabling

Authors: Enrico Bortoletto, Niels Lindner, and Berenike Masing

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
Periodic timetabling is a central aspect of both the long-term organization and the day-to-day operations of a public transportation system. The Periodic Event Scheduling Problem (PESP), the combinatorial optimization problem that forms the mathematical basis of periodic timetabling, is an extremely hard problem, for which optimal solutions are hardly ever found in practice. The most prominent solving strategies today are based on mixed-integer programming, and there is a concurrent PESP solver employing a wide range of heuristics [Borndörfer et al., 2020]. We present tropical neighborhood search (tns), a novel PESP heuristic. The method is based on the relations between periodic timetabling and tropical geometry [Bortoletto et al., 2022]. We implement tns into the concurrent solver, and test it on instances of the benchmarking library PESPlib. The inclusion of tns turns out to be quite beneficial to the solver: tns is able to escape local optima for the modulo network simplex algorithm, and the overall share of improvement coming from tns is substantial compared to the other methods available in the solver. Finally, we provide better primal bounds for five PESPlib instances.

Cite as

Enrico Bortoletto, Niels Lindner, and Berenike Masing. Tropical Neighbourhood Search: A New Heuristic for Periodic Timetabling. In 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 3:1-3:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{bortoletto_et_al:OASIcs.ATMOS.2022.3,
  author =	{Bortoletto, Enrico and Lindner, Niels and Masing, Berenike},
  title =	{{Tropical Neighbourhood Search: A New Heuristic for Periodic Timetabling}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{3:1--3:19},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022.3},
  URN =		{urn:nbn:de:0030-drops-171075},
  doi =		{10.4230/OASIcs.ATMOS.2022.3},
  annote =	{Keywords: Periodic Timetabling, Tropical Geometry, Neighborhood Search, Mixed-Integer Programming}
}
Document
Greedy Algorithms for the Freight Consolidation Problem

Authors: Zuguang Gao, John R. Birge, Richard Li-Yang Chen, and Maurice Cheung

Published in: OASIcs, Volume 106, 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)


Abstract
We define and study the (ocean) freight consolidation problem (FCP), which plays a crucial role in solving today’s supply chain crisis. Roughly speaking, every day and every hour, a freight forwarder sees a set of shipments and a set of containers at the origin port. There is a shipment cost associated with assigning each shipment to each container. If a container is assigned any shipment, there is also a procurement cost for that container. The FCP aims to minimize the total cost of fulfilling all the shipments, subject to capacity constraints of the containers. In this paper, we show that no constant factor approximation exists for FCP, and propose a series of greedy based heuristics for solving the problem. We also test our heuristics with simulated data and show that our heuristics achieve small optimality gaps.

Cite as

Zuguang Gao, John R. Birge, Richard Li-Yang Chen, and Maurice Cheung. Greedy Algorithms for the Freight Consolidation Problem. In 22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022). Open Access Series in Informatics (OASIcs), Volume 106, pp. 4:1-4:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


Copy BibTex To Clipboard

@InProceedings{gao_et_al:OASIcs.ATMOS.2022.4,
  author =	{Gao, Zuguang and Birge, John R. and Chen, Richard Li-Yang and Cheung, Maurice},
  title =	{{Greedy Algorithms for the Freight Consolidation Problem}},
  booktitle =	{22nd Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2022)},
  pages =	{4:1--4:19},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-259-4},
  ISSN =	{2190-6807},
  year =	{2022},
  volume =	{106},
  editor =	{D'Emidio, Mattia and Lindner, Niels},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2022.4},
  URN =		{urn:nbn:de:0030-drops-171086},
  doi =		{10.4230/OASIcs.ATMOS.2022.4},
  annote =	{Keywords: Freight consolidation, heuristics, greedy algorithm}
}
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