5 Search Results for "Wagner, Christian"

Document
DOI: 10.4230/LIPIcs.MFCS.2017.33
Emptiness Problems for Integer Circuits

Authors: Dominik Barth, Moritz Beck, Titus Dose, Christian Glaßer, Larissa Michler, and Marc Technau

Published in: LIPIcs, Volume 83, 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017)

Abstract
We study the computational complexity of emptiness problems for circuits over sets of natural numbers with the operations union, intersection, complement, addition, and multiplication. For most settings of allowed operations we precisely characterize the complexity in terms of completeness for classes like NL, NP, and PSPACE. The case where intersection, addition, and multiplication is allowed turns out to be equivalent to the complement of polynomial identity testing (PIT). Our results imply the following improvements and insights on problems studied in earlier papers. We improve the bounds for the membership problem MC(\cup,\cap,¯,+,×) studied by McKenzie and Wagner 2007 and for the equivalence problem EQ(\cup,\cap,¯,+,×) studied by Glaßer et al. 2010. Moreover, it turns out that the following problems are equivalent to PIT, which shows that the challenge to improve their bounds is just a reformulation of a major open problem in algebraic computing complexity: 1. membership problem MC(\cap,+,×) studied by McKenzie and Wagner 2007 2. integer membership problems MC_Z(+,×), MC_Z(\cap,+,×) studied by Travers 2006 3. equivalence problem EQ(+,×) studied by Glaßer et al. 2010
Cite as

Dominik Barth, Moritz Beck, Titus Dose, Christian Glaßer, Larissa Michler, and Marc Technau. Emptiness Problems for Integer Circuits. In 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 83, pp. 33:1-33:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{barth_et_al:LIPIcs.MFCS.2017.33,
  author =	{Barth, Dominik and Beck, Moritz and Dose, Titus and Gla{\ss}er, Christian and Michler, Larissa and Technau, Marc},
  title =	{{Emptiness Problems for Integer Circuits}},
  booktitle =	{42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017)},
  pages =	{33:1--33:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-046-0},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{83},
  editor =	{Larsen, Kim G. and Bodlaender, Hans L. and Raskin, Jean-Francois},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2017.33},
  URN =		{urn:nbn:de:0030-drops-80641},
  doi =		{10.4230/LIPIcs.MFCS.2017.33},
  annote =	{Keywords: computational complexity, integer expressions, integer circuits, polynomial identity testing}
}
Document
DOI: 10.4230/LIPIcs.ESA.2017.11
Modeling and Engineering Constrained Shortest Path Algorithms for Battery Electric Vehicles

Authors: Moritz Baum, Julian Dibbelt, Dorothea Wagner, and Tobias Zündorf

Published in: LIPIcs, Volume 87, 25th Annual European Symposium on Algorithms (ESA 2017)

Abstract
We study the problem of computing constrained shortest paths for battery electric vehicles. Since battery capacities are limited, fastest routes are often infeasible. Instead, users are interested in fast routes where the energy consumption does not exceed the battery capacity. For that, drivers can deliberately reduce speed to save energy. Hence, route planning should provide both path and speed recommendations. To tackle the resulting NP-hard optimization problem, previous work trades correctness or accuracy of the underlying model for practical running times. In this work, we present a novel framework to compute optimal constrained shortest paths for electric vehicles that uses more realistic physical models, while taking speed adaptation into account. Careful algorithm engineering makes the approach practical even on large, realistic road networks: We compute optimal solutions in less than a second for typical battery capacities, matching performance of previous inexact methods. For even faster performance, the approach can easily be extended with heuristics that provide high quality solutions within milliseconds.
Cite as

Moritz Baum, Julian Dibbelt, Dorothea Wagner, and Tobias Zündorf. Modeling and Engineering Constrained Shortest Path Algorithms for Battery Electric Vehicles. In 25th Annual European Symposium on Algorithms (ESA 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 87, pp. 11:1-11:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{baum_et_al:LIPIcs.ESA.2017.11,
  author =	{Baum, Moritz and Dibbelt, Julian and Wagner, Dorothea and Z\"{u}ndorf, Tobias},
  title =	{{Modeling and Engineering Constrained Shortest Path Algorithms for Battery Electric Vehicles}},
  booktitle =	{25th Annual European Symposium on Algorithms (ESA 2017)},
  pages =	{11:1--11:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-049-1},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{87},
  editor =	{Pruhs, Kirk and Sohler, Christian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2017.11},
  URN =		{urn:nbn:de:0030-drops-78672},
  doi =		{10.4230/LIPIcs.ESA.2017.11},
  annote =	{Keywords: electric vehicles, constrained shortest paths, algorithm engineering}
}
Document
DOI: 10.4230/OASIcs.VLUDS.2010.82
Open Problems in Computational Steering of Massive Parallel Unstructured Grid Based CFD Simulations

Authors: Christian Wagner

Published in: OASIcs, Volume 19, Visualization of Large and Unstructured Data Sets - Applications in Geospatial Planning, Modeling and Engineering (IRTG 1131 Workshop) (2011)

Abstract
Traditionally, analysis of flow fields resulting from computational fluid dynamics (CFD) calculations is a sequential process. The flow area defined by surrounding geometry is tessellated, a mesh is generated and divided into subregions, transferred to a cluster or supercomputer and the result is transferred back. Then, a variety of post-processing tasks should give insights to the physical problem. At that point, parameters chosen wrong can be identified and the simulation has to be done again with tweaked parameters. This is an iterative process that can be time consuming, especially if one iteration lasts more than a few days. In general, aiming at reducing the simulation times by shortening the time used to identify wrong parameters results in high productivity enhancements. In this paper, the need for on-line monitoring and computational steering approaches for massive parallel unstructured flow simulators are presented with aircraft design as one of many possible application domains. This involves software integration aspects, data streaming and explorative visualization. Many challenges still have to be solved and this paper summarizes most important ones.
Cite as

Christian Wagner. Open Problems in Computational Steering of Massive Parallel Unstructured Grid Based CFD Simulations. In Visualization of Large and Unstructured Data Sets - Applications in Geospatial Planning, Modeling and Engineering (IRTG 1131 Workshop). Open Access Series in Informatics (OASIcs), Volume 19, pp. 82-89, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)

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@InProceedings{wagner:OASIcs.VLUDS.2010.82,
  author =	{Wagner, Christian},
  title =	{{Open Problems in Computational Steering of Massive Parallel Unstructured Grid Based CFD Simulations}},
  booktitle =	{Visualization of Large and Unstructured Data Sets - Applications in Geospatial Planning, Modeling and Engineering (IRTG 1131 Workshop)},
  pages =	{82--89},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-29-3},
  ISSN =	{2190-6807},
  year =	{2011},
  volume =	{19},
  editor =	{Middel, Ariane and Scheler, Inga and Hagen, Hans},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.VLUDS.2010.82},
  URN =		{urn:nbn:de:0030-drops-31002},
  doi =		{10.4230/OASIcs.VLUDS.2010.82},
  annote =	{Keywords: Computational Steering, CFD simulation, Interactive Visualization, Explorative Visualization, Virtual Reality}
}
Document
DOI: 10.4230/DagSemProc.09201.9
Component-Oriented Behavior Extraction for Autonomic System Design

Authors: Tiziana Margaria, Marco Bakera, and Christian Wagner

Published in: Dagstuhl Seminar Proceedings, Volume 9201, Self-Healing and Self-Adaptive Systems (2009)

Abstract
Rich and multifaceted domain specific specification languages like the Autonomic System Specification Language (ASSL) help to design reliable systems with self-healing capabilities. The GEAR game-based Model Checker has been used successfully to investigate properties of the ESA Exo- Mars Rover in depth. We show here how to enable GEAR’s game-based verification techniques for ASSL via systematic model extraction from a behavioral subset of the language, and illustrate it on a description of the Voyager II space mission.
Cite as

Tiziana Margaria, Marco Bakera, and Christian Wagner. Component-Oriented Behavior Extraction for Autonomic System Design. In Self-Healing and Self-Adaptive Systems. Dagstuhl Seminar Proceedings, Volume 9201, pp. 1-2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2009)

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@InProceedings{margaria_et_al:DagSemProc.09201.9,
  author =	{Margaria, Tiziana and Bakera, Marco and Wagner, Christian},
  title =	{{Component-Oriented Behavior Extraction for Autonomic System Design}},
  booktitle =	{Self-Healing and Self-Adaptive Systems},
  pages =	{1--2},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2009},
  volume =	{9201},
  editor =	{Artur Andrzejak and Kurt Geihs and Onn Shehory and John Wilkes},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.09201.9},
  URN =		{urn:nbn:de:0030-drops-20964},
  doi =		{10.4230/DagSemProc.09201.9},
  annote =	{Keywords: Self-healing, model driven design, game based model checking, model extraction}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2007.1169
14. Experimental Study on Speed-Up Techniques for Timetable Information Systems

Authors: Reinhard Bauer, Daniel Delling, and Dorothea Wagner

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

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

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

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