27 Search Results for "Bouman, Paul"

Volume

OASIcs, Volume 123

24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)

ATMOS 2024, September 5-6, 2024, Royal Holloway, London, United Kingdom

Editors: Paul C. Bouman and Spyros C. Kontogiannis

Document
DOI: 10.4230/OASIcs.ATMOS.2025.11
Design of Distance Tariffs in Public Transport

Authors: Philine Schiewe, Anita Schöbel, and Reena Urban

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

Abstract
Setting the ticket prices is a crucial decision in public transport. Its basis, relevant for all related questions, such as dynamic prices or prices for different passenger groups, is the underlying fare strategy. Popular fare strategies are based on zones or on distances. Transitions from one fare strategy to another occur frequently, e.g., if public transport operators are joined to a larger association, or if structural decisions in a region have taken place. In this paper we report practically relevant issues when a fare structure should be changed to a distance tariff, a problem frequently arising when a ticket system based on mobile devices is introduced. We present mixed-integer linear programs for finding the parameters of a distance tariff, analyze rounding properties, and reflect how the change in revenue for the operator and the number of highly affected passengers can be controlled. Additionally, we evaluate the developed models experimentally.
Cite as

Philine Schiewe, Anita Schöbel, and Reena Urban. Design of Distance Tariffs in Public Transport. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 11:1-11:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{schiewe_et_al:OASIcs.ATMOS.2025.11,
  author =	{Schiewe, Philine and Sch\"{o}bel, Anita and Urban, Reena},
  title =	{{Design of Distance Tariffs in Public Transport}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{11:1--11:20},
  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.2025.11},
  URN =		{urn:nbn:de:0030-drops-247670},
  doi =		{10.4230/OASIcs.ATMOS.2025.11},
  annote =	{Keywords: public transport, fare strategy, distance tariff}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2025.14
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
DOI: 10.4230/OASIcs.ATMOS.2025.1
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
Complete Volume
DOI: 10.4230/OASIcs.ATMOS.2024
OASIcs, Volume 123, ATMOS 2024, Complete Volume

Authors: Paul C. Bouman and Spyros C. Kontogiannis

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

Abstract
OASIcs, Volume 123, ATMOS 2024, Complete Volume
Cite as

24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 1-316, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Proceedings{bouman_et_al:OASIcs.ATMOS.2024,
  title =	{{OASIcs, Volume 123, ATMOS 2024, Complete Volume}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{1--316},
  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},
  URN =		{urn:nbn:de:0030-drops-211873},
  doi =		{10.4230/OASIcs.ATMOS.2024},
  annote =	{Keywords: OASIcs, Volume 123, ATMOS 2024, Complete Volume}
}
Document
Front Matter
DOI: 10.4230/OASIcs.ATMOS.2024.0
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Paul C. Bouman and Spyros C. Kontogiannis

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

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

24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 0:i-0:xii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{bouman_et_al:OASIcs.ATMOS.2024.0,
  author =	{Bouman, Paul C. and Kontogiannis, Spyros C.},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{0:i--0:xii},
  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.2024.0},
  URN =		{urn:nbn:de:0030-drops-211882},
  doi =		{10.4230/OASIcs.ATMOS.2024.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.1
Landmark Hub Labeling: Improved Bounds and Faster Query Answering

Authors: Justine Cauvi, Ruoying Li, and Sabine Storandt

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

Abstract
Hub Labeling (HL) is a state-of-the-art method for answering shortest-distance queries between node pairs in weighted graphs. It provides very fast query times but also requires considerable additional space to store the label information. Recently, a generalization of HL, called Landmark Hub Labeling (LHL), has been proposed, that conceptionally allows a storage of fewer label information without compromising the optimality of the query result. However, query answering with LHL was shown to be slower than with HL, both in theory and practice. Furthermore, it was not clear whether there are graphs with a substantial space reduction when using LHL instead of HL. In this paper, we describe a new way of storing label information of an LHL such that query times are significantly reduced and then asymptotically match those of HL. Thus, we alleviate the so far greatest shortcoming of LHL compared to HL. Moreover, we show that for the practically relevant hierarchical versions (HHL and HLHL), there are graphs in which the label size of an optimal HLHL is a factor of Θ(√ n) smaller than that of an optimal HHL. We establish further novel bounds between different labeling variants. Additionally, we provide a comparative experimental study between approximation algorithms for HL and LHL. We demonstrate that label sizes in an LHL are consistently smaller than those of HL across diverse benchmark graphs, including road networks.
Cite as

Justine Cauvi, Ruoying Li, and Sabine Storandt. Landmark Hub Labeling: Improved Bounds and Faster Query Answering. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 1:1-1:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{cauvi_et_al:OASIcs.ATMOS.2024.1,
  author =	{Cauvi, Justine and Li, Ruoying and Storandt, Sabine},
  title =	{{Landmark Hub Labeling: Improved Bounds and Faster Query Answering}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{1:1--1:17},
  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.2024.1},
  URN =		{urn:nbn:de:0030-drops-211892},
  doi =		{10.4230/OASIcs.ATMOS.2024.1},
  annote =	{Keywords: Route Planning, Shortest Path, Hub Labeling}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.2
Indexing Graphs for Shortest Beer Path Queries

Authors: David Coudert, Andrea D'Ascenzo, and Mattia D'Emidio

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

Abstract
A beer graph is an edge-weighted graph G = (V,E,ω) with beer vertices B ⊆ V. A beer path between two vertices s and t of a beer graph is a path that connects s and t and visits at least one vertex in B. The beer distance between two vertices is the weight of a shortest beer path, i.e. a beer path having minimum total weight. A graph indexing scheme is a two-phase method that constructs an index data structure by a one-time preprocessing of an input graph and then exploits it to compute (or accelerate the computation of) answers to queries on structures of the graph dataset. In the last decade, such indexing schemes have been designed to perform, effectively, many relevant types of queries, e.g. on reachability, and have gained significant popularity in essentially all data-intensive application domains where large number of queries have to be routinely answered (e.g. journey planners), since they have been shown, through many experimental studies, to offer extremely low query times at the price of limited preprocessing time and space overheads. In this paper, we showcase that an indexing scheme, to efficiently execute queries on beer distances or shortest beer paths for pairs of vertices of a beer graph, can be obtained by adapting the highway labeling, a recently introduced indexing method to accelerate the computation of classical shortest paths. We design a preprocessing algorithm to build a whl index, i.e. a weighted highway labeling of a beer graph, and show how it can be queried to compute beer distances and shortest beer paths. Through extensive experimentation on real networks, we empirically demonstrate its practical effectiveness and superiority, in terms of offered trade-off between preprocessing time, space overhead and query time, with respect to the state-of-the-art.
Cite as

David Coudert, Andrea D'Ascenzo, and Mattia D'Emidio. Indexing Graphs for Shortest Beer Path Queries. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 2:1-2:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{coudert_et_al:OASIcs.ATMOS.2024.2,
  author =	{Coudert, David and D'Ascenzo, Andrea and D'Emidio, Mattia},
  title =	{{Indexing Graphs for Shortest Beer Path Queries}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{2:1--2:18},
  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.2024.2},
  URN =		{urn:nbn:de:0030-drops-211907},
  doi =		{10.4230/OASIcs.ATMOS.2024.2},
  annote =	{Keywords: Graph Algorithms, Indexing Schemes, Beer Distances, Algorithms Engineering}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.3
Pricing for the EVRPTW with Piecewise Linear Charging by a Bounding-Based Labeling Algorithm

Authors: Jenny Enerbäck, Lukas Eveborn, and Elina Rönnberg

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

Abstract
The elementary shortest path problem with resource constraints (ESPPRC) is a common problem that often arises as a pricing problem when solving vehicle routing problems with a column generation approach. One way of solving the ESPPRC is to use a labeling algorithm. In this paper, we focus on how different bounding strategies for labeling algorithms can be adapted and strengthened for the ESPPRC that arises from the Electric Vehicle Routing Problem with Time Windows and Piecewise Linear Recharging function (EVRPTW-PLR). We present a new completion bound method that takes charging times into account, and show how the completion bound can be combined with ng-routes. Computational experiments show that the new completion bound combined with ng-routes significantly improves the performance compared to a basic labeling algorithm.
Cite as

Jenny Enerbäck, Lukas Eveborn, and Elina Rönnberg. Pricing for the EVRPTW with Piecewise Linear Charging by a Bounding-Based Labeling Algorithm. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 3:1-3:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{enerback_et_al:OASIcs.ATMOS.2024.3,
  author =	{Enerb\"{a}ck, Jenny and Eveborn, Lukas and R\"{o}nnberg, Elina},
  title =	{{Pricing for the EVRPTW with Piecewise Linear Charging by a Bounding-Based Labeling Algorithm}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{3:1--3:18},
  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.2024.3},
  URN =		{urn:nbn:de:0030-drops-211911},
  doi =		{10.4230/OASIcs.ATMOS.2024.3},
  annote =	{Keywords: ESPPRC, EVRP, Bounding, Labeling Algorithm}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.4
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
DOI: 10.4230/OASIcs.ATMOS.2024.5
Balanced Assignments of Periodic Tasks

Authors: Héloïse Gachet and Frédéric Meunier

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

Abstract
This work deals with a problem of assigning periodic tasks to employees in such a way that each employee performs each task with the same frequency in the long term. The motivation comes from a collaboration with the main French railway company, the SNCF. An almost complete solution is provided under the form of a necessary and sufficient condition that can be checked in polynomial time. A complementary discussion about possible extensions is also proposed.
Cite as

Héloïse Gachet and Frédéric Meunier. Balanced Assignments of Periodic Tasks. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 5:1-5:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{gachet_et_al:OASIcs.ATMOS.2024.5,
  author =	{Gachet, H\'{e}lo\"{i}se and Meunier, Fr\'{e}d\'{e}ric},
  title =	{{Balanced Assignments of Periodic Tasks}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{5:1--5:12},
  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.2024.5},
  URN =		{urn:nbn:de:0030-drops-211938},
  doi =		{10.4230/OASIcs.ATMOS.2024.5},
  annote =	{Keywords: Fair schedule, Eulerian digraph, Markov chain, interval graph}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.6
Two-Stage Weekly Shift Scheduling for Train Dispatchers

Authors: Tomas Lidén, Christiane Schmidt, and Rabii Zahir

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

Abstract
We consider the problem of creating weekly shift schedules for train dispatchers, which conform to a variety of operational constraints, in particular, several work and rest time restrictions. We create the schedules in a two-stage process. First, using a previously presented IP model, we create a set of feasible daily shifts, which takes care of minimum-rest and shift-length requirements, taskload bounds, and combinability of dispatching areas. We then formulate an IP model to combine these daily shifts into weekly schedules, enforcing that each daily shift is covered by some dispatcher every day of the week, while ensuring that the weekly schedules comply with various restrictions on working hours from a union agreement. With this approach, we aim to identify "good" sets of daily shifts for the longer schedules. We run experiments for real-world sized input and consider different distributions of the daily shifts w.r.t. shift length and ratio of night shifts. Daily shifts with shift-length variability, relatively few long shifts, and a low ratio of night shifts generally yield better weekly schedules. The runtime for the second stage with the best daily-shift pattern is below three hours, which - together with the runtime for stage 1 of ca. 2 hours per run - can be feasible for real-world use.
Cite as

Tomas Lidén, Christiane Schmidt, and Rabii Zahir. Two-Stage Weekly Shift Scheduling for Train Dispatchers. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 6:1-6:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{liden_et_al:OASIcs.ATMOS.2024.6,
  author =	{Lid\'{e}n, Tomas and Schmidt, Christiane and Zahir, Rabii},
  title =	{{Two-Stage Weekly Shift Scheduling for Train Dispatchers}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{6:1--6:16},
  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.2024.6},
  URN =		{urn:nbn:de:0030-drops-211944},
  doi =		{10.4230/OASIcs.ATMOS.2024.6},
  annote =	{Keywords: shift scheduling, IP, train dispatcher shift scheduling}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.7
Improved Algorithms for the Capacitated Team Orienteering Problem

Authors: Gianlorenzo D'Angelo, Mattia D'Emidio, Esmaeil Delfaraz, and Gabriele Di Stefano

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

Abstract
We study the Capacitated Team Orienteering Problem, where a fleet of vehicles with capacities have to meet customers with known demands and prizes for a single commodity. The objective is to maximize the total prize and to assign a sequence of customers to each vehicle while keeping the total distance traveled within a given budget and such that the total demand served by each vehicle does not exceed its capacity. The problem has been widely studied both from a theoretical and a practical point of view. The contribution of this paper is twofold: (1) We advance the theoretical knowledge on the problem by providing new approximation algorithms that achieve, under some natural assumption, improved approximation ratios compared to the current best algorithms; (2) We propose four efficient heuristics that outperform the current state-of-the-art practical methods in the sense that they compute solutions that collect nearly the same prize in a significantly smaller running time. We also experimentally test the scalability of the new heuristics, showing that their running time increases approximately linearly with the size of the input, allowing us to process large graphs which were not possible to analyze before.
Cite as

Gianlorenzo D'Angelo, Mattia D'Emidio, Esmaeil Delfaraz, and Gabriele Di Stefano. Improved Algorithms for the Capacitated Team Orienteering Problem. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 7:1-7:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{dangelo_et_al:OASIcs.ATMOS.2024.7,
  author =	{D'Angelo, Gianlorenzo and D'Emidio, Mattia and Delfaraz, Esmaeil and Di Stefano, Gabriele},
  title =	{{Improved Algorithms for the Capacitated Team Orienteering Problem}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{7:1--7:17},
  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.2024.7},
  URN =		{urn:nbn:de:0030-drops-211957},
  doi =		{10.4230/OASIcs.ATMOS.2024.7},
  annote =	{Keywords: Vehicle Routing, Approximation algorithms, Algorithm Engineering}
}
Document
Short Paper
DOI: 10.4230/OASIcs.ATMOS.2024.8
New Bounds on the Performance of SBP for the Dial-a-Ride Problem with Revenues (Short Paper)

Authors: Barbara M. Anthony, Christine Chung, Ananya Das, and David Yuen

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

Abstract
We revisit the Segmented Best Path (sbp) algorithm for online DARP in an offline setting with revenues and a time limit. The goal is to find a subset of the inputted ride requests that can be served within the time limit while maximizing the total revenue earned. sbp divides the time into segments and greedily chooses the highest-revenue path of requests to serve within each time segment. We show that sbp’s performance has an upper bound of 5. Further, while sbp is a tight 4-approximation in the uniform-revenue case, we find that with non-uniform revenues, the approximation ratio of sbp has a lower bound strictly greater than 4; in particular, we provide a lower bound of (√e + 1)/(√e - 1) ≈ 4.08299, which we show can be generalized to instances with ratio greater than 4.278.
Cite as

Barbara M. Anthony, Christine Chung, Ananya Das, and David Yuen. New Bounds on the Performance of SBP for the Dial-a-Ride Problem with Revenues (Short Paper). In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 8:1-8:6, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{anthony_et_al:OASIcs.ATMOS.2024.8,
  author =	{Anthony, Barbara M. and Chung, Christine and Das, Ananya and Yuen, David},
  title =	{{New Bounds on the Performance of SBP for the Dial-a-Ride Problem with Revenues}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{8:1--8:6},
  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.2024.8},
  URN =		{urn:nbn:de:0030-drops-211964},
  doi =		{10.4230/OASIcs.ATMOS.2024.8},
  annote =	{Keywords: Dial-a-Ride problems, Lower bounds, Vehicle routing}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2024.9
Online Vehicle Routing with Pickups and Deliveries Under Time-Dependent Travel-Time Constraints

Authors: Spyros Kontogiannis, Andreas Paraskevopoulos, and Christos Zaroliagis

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

Abstract
The Vehicle Routing Problem with pickups, deliveries and spatiotemporal service constraints (VRP_PDSTC) is a quite challenging algorithmic problem that can be dealt with in either an offline or an online fashion. In this work, we focus on a generalization, called VRP_PDSTCtd, in which the travel-time metric is time-dependent: the traversal-time per road segment (represented as a directed arc) is determined by some function of the departure-time from its tail towards its head. Time-dependence makes things much more complicated, even for the simpler problem of computing earliest-arrival-time paths which is a crucial subroutine to be solved (numerous times) by VRP_PDSTCtd schedulers. We propose two online schedulers of requests to workers, one which is a time-dependent variant of the classical Plain-Insertion heuristic, and an extension of it trying to digest some sort of forecasts for future demands for service. We enrich these two online schedulers with two additional heuristics, one targeting for distance-balanced assignments of work loads to the workers and another that makes local-search-improvements to the produced solutions. We conduct a careful experimental evaluation of the proposed algorithms on a real-world instance, with or without these heuristics, and compare their quality with human-curated assignments provided by professional experts (human operators at actual pickup-and-delivery control centers), and also with feasible solutions constructed from a relaxed MILP formulation of VRP_PDSTCtd, which is also introduced in this paper. Our findings are quite encouraging, demonstrating that the proposed algorithms produce solutions which (i) are significant improvements over the human-curated assignments, and (ii) have overall quality pretty close to that of the (extremely time-consuming) solutions provided by an exact solver for the MILP formulation.
Cite as

Spyros Kontogiannis, Andreas Paraskevopoulos, and Christos Zaroliagis. Online Vehicle Routing with Pickups and Deliveries Under Time-Dependent Travel-Time Constraints. In 24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024). Open Access Series in Informatics (OASIcs), Volume 123, pp. 9:1-9:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{kontogiannis_et_al:OASIcs.ATMOS.2024.9,
  author =	{Kontogiannis, Spyros and Paraskevopoulos, Andreas and Zaroliagis, Christos},
  title =	{{Online Vehicle Routing with Pickups and Deliveries Under Time-Dependent Travel-Time Constraints}},
  booktitle =	{24th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2024)},
  pages =	{9:1--9:20},
  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.2024.9},
  URN =		{urn:nbn:de:0030-drops-211972},
  doi =		{10.4230/OASIcs.ATMOS.2024.9},
  annote =	{Keywords: transport optimization heuristics, vehicle routing with pickups and deliveries, time-dependent travel-times}
}
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