6 Search Results for "Zündorf, Michael"

Document
DOI: 10.4230/OASIcs.ATMOS.2025.15
Exact and Heuristic Dynamic Taxi Sharing with Transfers Using Shortest-Path Speedup Techniques

Authors: Johannes Breitling and Moritz Laupichler

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

Abstract
We introduce a first-of-its-kind efficient, exact algorithm for the dynamic taxi-sharing problem with single-transfer journeys, i.e., a dispatcher that assigns traveler requests to a fleet of shared taxi-like vehicles allowing transfers between vehicles. We extend an existing no-transfer solution by collecting all viable pickup and dropoff vehicles for a request and computing the optimal transfer point for every pair of vehicles. We analyze underlying shortest-path problems and employ state-of-the-art routing algorithms to compute distances on-the-fly, which serves as the basis of dispatching requests with exact and up-to-date travel time information. We utilize constraints on existing routes, pruning techniques for transfer points, and both instruction- and thread-level parallelism to speed up the computation of the best assignment for every traveler. In addition to the exact variant, we propose a tunable heuristic approach that sacrifices solution quality in favor of improved running time. We evaluate our algorithm on a large road network with realistic input sets (up to 150000 requests). We demonstrate the effectiveness of our speedup techniques and the heuristic. We show first results on the benefits of transfers for taxi sharing on dense request sets, proving that our algorithm is well suited for the analysis of taxi sharing with transfers on large input instances.
Cite as

Johannes Breitling and Moritz Laupichler. Exact and Heuristic Dynamic Taxi Sharing with Transfers Using Shortest-Path Speedup Techniques. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 15:1-15:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{breitling_et_al:OASIcs.ATMOS.2025.15,
  author =	{Breitling, Johannes and Laupichler, Moritz},
  title =	{{Exact and Heuristic Dynamic Taxi Sharing with Transfers Using Shortest-Path Speedup Techniques}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{15:1--15:22},
  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.2025.15},
  URN =		{urn:nbn:de:0030-drops-247718},
  doi =		{10.4230/OASIcs.ATMOS.2025.15},
  annote =	{Keywords: Dynamic taxi sharing, ride pooling, dial-a-ride problem, transfers, route planning}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2025.12
Separator-Based Alternative Paths in Customizable Contraction Hierarchies

Authors: Scott Bacherle, Thomas Bläsius, and Michael Zündorf

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

Abstract
We propose an algorithm for computing alternatives to the shortest path in a road network, based on the speed-up technique CCH (customizable contraction hierarchy). Computing alternative paths is a well-studied problem, motivated by the fact that route-planning applications benefit from presenting different high-quality options the user can choose from. Another crucial feature of modern routing applications is the inclusion of live traffic, which requires speed-up techniques that allow efficient metric updates. Besides CCH, the other speed-up technique supporting metric updates is CRP (customizable route planning). Of the two, CCH is the more modern solution with the advantages of providing faster queries and being substantially simpler to implement efficiently. However, so far, CCH has been lacking a way of computing alternative paths. While for CRP, the commonly used plateau method for computing alternatives can be applied, this is not so straightforward for CCH. With this paper, we make CCH a viable option for alternative paths, by proposing a new separator-based approach to computing alternative paths that works hand-in-hand with the CCH data structure. With our experiments, we demonstrate that CCH can indeed be used to compute alternative paths efficiently. With this, we provide an alternative to CRP that is simpler and has lower query times.
Cite as

Scott Bacherle, Thomas Bläsius, and Michael Zündorf. Separator-Based Alternative Paths in Customizable Contraction Hierarchies. In 25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025). Open Access Series in Informatics (OASIcs), Volume 137, pp. 12:1-12:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{bacherle_et_al:OASIcs.ATMOS.2025.12,
  author =	{Bacherle, Scott and Bl\"{a}sius, Thomas and Z\"{u}ndorf, Michael},
  title =	{{Separator-Based Alternative Paths in Customizable Contraction Hierarchies}},
  booktitle =	{25th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2025)},
  pages =	{12:1--12:16},
  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.2025.12},
  URN =		{urn:nbn:de:0030-drops-247685},
  doi =		{10.4230/OASIcs.ATMOS.2025.12},
  annote =	{Keywords: Alternative routes, realistic road networks, customizable contraction hierarchies, route planning, shortest paths}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2021.11
Robustness Generalizations of the Shortest Feasible Path Problem for Electric Vehicles

Authors: Payas Rajan, Moritz Baum, Michael Wegner, Tobias Zündorf, Christian J. West, Dennis Schieferdecker, and Daniel Delling

Published in: OASIcs, Volume 96, 21st Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2021)

Abstract
Electric Vehicle routing is often modeled as a Shortest Feasible Path Problem (SFPP), which minimizes total travel time while maintaining a non-zero State of Charge (SoC) along the route. However, the problem assumes perfect information about energy consumption and charging stations, which are difficult to even estimate in practice. Further, drivers might have varying risk tolerances for different trips. To overcome these limitations, we propose two generalizations to the SFPP; they compute the shortest feasible path for any initial SoC and, respectively, for every possible minimum SoC threshold. We present algorithmic solutions for each problem, and provide two constructs: Starting Charge Maps and Buffer Maps, which represent the tradeoffs between robustness of feasible routes and their travel times. The two constructs are useful in many ways, including presenting alternate routes or providing charging prompts to users. We evaluate the performance of our algorithms on realistic input instances.
Cite as

Payas Rajan, Moritz Baum, Michael Wegner, Tobias Zündorf, Christian J. West, Dennis Schieferdecker, and Daniel Delling. Robustness Generalizations of the Shortest Feasible Path Problem for Electric Vehicles. In 21st Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2021). Open Access Series in Informatics (OASIcs), Volume 96, pp. 11:1-11:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{rajan_et_al:OASIcs.ATMOS.2021.11,
  author =	{Rajan, Payas and Baum, Moritz and Wegner, Michael and Z\"{u}ndorf, Tobias and West, Christian J. and Schieferdecker, Dennis and Delling, Daniel},
  title =	{{Robustness Generalizations of the Shortest Feasible Path Problem for Electric Vehicles}},
  booktitle =	{21st Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2021)},
  pages =	{11:1--11:18},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-213-6},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{96},
  editor =	{M\"{u}ller-Hannemann, Matthias and Perea, Federico},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2021.11},
  URN =		{urn:nbn:de:0030-drops-148807},
  doi =		{10.4230/OASIcs.ATMOS.2021.11},
  annote =	{Keywords: Electric Vehicles, Route Planning}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2020.9
Customizable Contraction Hierarchies with Turn Costs

Authors: Valentin Buchhold, Dorothea Wagner, Tim Zeitz, and Michael Zündorf

Published in: OASIcs, Volume 85, 20th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2020)

Abstract
We incorporate turn restrictions and turn costs into the route planning algorithm customizable contraction hierarchies (CCH). There are two common ways to represent turn costs and restrictions. The edge-based model expands the network so that road segments become vertices and allowed turns become edges. The compact model keeps intersections as vertices, but associates a turn table with each vertex. Although CCH can be used as is on the edge-based model, the performance of preprocessing and customization is severely affected. While the expanded network is only three times larger, both preprocessing and customization time increase by up to an order of magnitude. In this work, we carefully engineer CCH to exploit different properties of the expanded graph. We reduce the increase in customization time from up to an order of magnitude to a factor of about 3. The increase in preprocessing time is reduced even further. Moreover, we present a CCH variant that works on the compact model, and show that it performs worse than the variant on the edge-based model. Surprisingly, the variant on the edge-based model even uses less space than the one on the compact model, although the compact model was developed to keep the space requirement low.
Cite as

Valentin Buchhold, Dorothea Wagner, Tim Zeitz, and Michael Zündorf. Customizable Contraction Hierarchies with Turn Costs. In 20th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2020). Open Access Series in Informatics (OASIcs), Volume 85, pp. 9:1-9:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{buchhold_et_al:OASIcs.ATMOS.2020.9,
  author =	{Buchhold, Valentin and Wagner, Dorothea and Zeitz, Tim and Z\"{u}ndorf, Michael},
  title =	{{Customizable Contraction Hierarchies with Turn Costs}},
  booktitle =	{20th Symposium on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2020)},
  pages =	{9:1--9:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-170-2},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{85},
  editor =	{Huisman, Dennis and Zaroliagis, Christos D.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2020.9},
  URN =		{urn:nbn:de:0030-drops-131453},
  doi =		{10.4230/OASIcs.ATMOS.2020.9},
  annote =	{Keywords: Turn costs, realistic road networks, customizable contraction hierarchies, route planning, shortest paths}
}
Document
DOI: 10.4230/LIPIcs.ESA.2019.14
UnLimited TRAnsfers for Multi-Modal Route Planning: An Efficient Solution

Authors: Moritz Baum, Valentin Buchhold, Jonas Sauer, Dorothea Wagner, and Tobias Zündorf

Published in: LIPIcs, Volume 144, 27th Annual European Symposium on Algorithms (ESA 2019)

Abstract
We study a multi-modal route planning scenario consisting of a public transit network and a transfer graph representing a secondary transportation mode (e.g., walking or taxis). The objective is to compute all journeys that are Pareto-optimal with respect to arrival time and the number of required transfers. While various existing algorithms can efficiently compute optimal journeys in either a pure public transit network or a pure transfer graph, combining the two increases running times significantly. As a result, even walking between stops is typically limited by a maximal duration or distance, or by requiring the transfer graph to be transitively closed. To overcome these shortcomings, we propose a novel preprocessing technique called ULTRA (UnLimited TRAnsfers): Given a complete transfer graph (without any limitations, representing an arbitrary non-schedule-based mode of transportation), we compute a small number of transfer shortcuts that are provably sufficient for computing all Pareto-optimal journeys. We demonstrate the practicality of our approach by showing that these transfer shortcuts can be integrated into a variety of state-of-the-art public transit algorithms, establishing the ULTRA-Query algorithm family. Our extensive experimental evaluation shows that ULTRA is able to improve these algorithms from limited to unlimited transfers without sacrificing query speed, yielding the fastest known algorithms for multi-modal routing. This is true not just for walking, but also for other transfer modes such as cycling or driving.
Cite as

Moritz Baum, Valentin Buchhold, Jonas Sauer, Dorothea Wagner, and Tobias Zündorf. UnLimited TRAnsfers for Multi-Modal Route Planning: An Efficient Solution. In 27th Annual European Symposium on Algorithms (ESA 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 144, pp. 14:1-14:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{baum_et_al:LIPIcs.ESA.2019.14,
  author =	{Baum, Moritz and Buchhold, Valentin and Sauer, Jonas and Wagner, Dorothea and Z\"{u}ndorf, Tobias},
  title =	{{UnLimited TRAnsfers for Multi-Modal Route Planning: An Efficient Solution}},
  booktitle =	{27th Annual European Symposium on Algorithms (ESA 2019)},
  pages =	{14:1--14:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-124-5},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{144},
  editor =	{Bender, Michael A. and Svensson, Ola and Herman, Grzegorz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2019.14},
  URN =		{urn:nbn:de:0030-drops-111352},
  doi =		{10.4230/LIPIcs.ESA.2019.14},
  annote =	{Keywords: Algorithms, Optimization, Route Planning, Public Transportation}
}
Document
DOI: 10.4230/DagSemProc.05402.1
Dagstuhl-Manifest zur Strategischen Bedeutung des Software Engineering in Deutschland

Authors: Manfred Broy, Matthias Jarke, Manfred Nagl, Hans Dieter Rombach, Armin B. Cremers, Jürgen Ebert, Sabine Glesner, Martin Glinz, Michael Goedicke, Gerhard Goos, Volker Gruhn, Wilhelm Hasselbring, Stefan Jähnichen, Stefan Kowalewski, Bernd J. Krämer, Stefan Leue, Claus Lewerentz, Peter Liggesmeyer, Christoph Lüth, Barbara Paech, Helmut A. Partsch, Ilka Philippow, Lutz Prechelt, Andreas Rausch, Willem-Paul de Roever, Bernhard Rumpe, Gudula Rünger, Wilhelm Schäfer, Kurt Schneider, Andy Schürr, Walter F. Tichy, Bernhard Westfechtel, Wolf Zimmermann, and Albert Zündorf

Published in: Dagstuhl Seminar Proceedings, Volume 5402, Perspectives Workshop (2006)

Abstract
Im Rahmen des Dagstuhl Perspektiven Workshop 05402 "Challenges for Software Engineering Research" haben führende Software Engineering Professoren den derzeitigen Stand der Softwaretechnik in Deutschland charakterisiert und Handlungsempfehlungen für Wirtschaft, Forschung und Politik abgeleitet. Das Manifest fasst die diese Empfehlungen und die Bedeutung und Entwicklung des Fachgebiets prägnant zusammen.
Cite as

Manfred Broy, Matthias Jarke, Manfred Nagl, Hans Dieter Rombach, Armin B. Cremers, Jürgen Ebert, Sabine Glesner, Martin Glinz, Michael Goedicke, Gerhard Goos, Volker Gruhn, Wilhelm Hasselbring, Stefan Jähnichen, Stefan Kowalewski, Bernd J. Krämer, Stefan Leue, Claus Lewerentz, Peter Liggesmeyer, Christoph Lüth, Barbara Paech, Helmut A. Partsch, Ilka Philippow, Lutz Prechelt, Andreas Rausch, Willem-Paul de Roever, Bernhard Rumpe, Gudula Rünger, Wilhelm Schäfer, Kurt Schneider, Andy Schürr, Walter F. Tichy, Bernhard Westfechtel, Wolf Zimmermann, and Albert Zündorf. Dagstuhl-Manifest zur Strategischen Bedeutung des Software Engineering in Deutschland. In Perspectives Workshop. Dagstuhl Seminar Proceedings, Volume 5402, pp. 1-16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{broy_et_al:DagSemProc.05402.1,
  author =	{Broy, Manfred and Jarke, Matthias and Nagl, Manfred and Rombach, Hans Dieter and Cremers, Armin B. and Ebert, J\"{u}rgen and Glesner, Sabine and Glinz, Martin and Goedicke, Michael and Goos, Gerhard and Gruhn, Volker and Hasselbring, Wilhelm and J\"{a}hnichen, Stefan and Kowalewski, Stefan and Kr\"{a}mer, Bernd J. and Leue, Stefan and Lewerentz, Claus and Liggesmeyer, Peter and L\"{u}th, Christoph and Paech, Barbara and Partsch, Helmut A. and Philippow, Ilka and Prechelt, Lutz and Rausch, Andreas and de Roever, Willem-Paul and Rumpe, Bernhard and R\"{u}nger, Gudula and Sch\"{a}fer, Wilhelm and Schneider, Kurt and Sch\"{u}rr, Andy and Tichy, Walter F. and Westfechtel, Bernhard and Zimmermann, Wolf and Z\"{u}ndorf, Albert},
  title =	{{Dagstuhl-Manifest zur Strategischen Bedeutung des Software Engineering in Deutschland}},
  booktitle =	{Perspectives Workshop},
  pages =	{1--16},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{5402},
  editor =	{Manfred Broy and Manfred Nagl and Hans Dieter Rombach and Matthias Jarke},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.05402.1},
  URN =		{urn:nbn:de:0030-drops-5853},
  doi =		{10.4230/DagSemProc.05402.1},
  annote =	{Keywords: Software Engineering, Software Technik, Strategie}
}
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