37 Search Results for "Held, Martin"


Document
New Frontiers of Parameterized Complexity in Graph Drawing (Dagstuhl Seminar 23162)

Authors: Robert Ganian, Fabrizio Montecchiani, Martin Nöllenburg, Meirav Zehavi, and Liana Khazaliya

Published in: Dagstuhl Reports, Volume 13, Issue 4 (2023)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 23162 "New Frontiers of Parameterized Complexity in Graph Drawing”. The seminar was held in-person from April 16 to April 21, 2023. It brought together 32 researchers from the Graph Drawing and the Parameterized Complexity research communities to discuss and explore new research frontiers on the interface between the two fields. The report collects the abstracts of talks and open problems presented in the seminar, as well as brief progress reports from the working groups.

Cite as

Robert Ganian, Fabrizio Montecchiani, Martin Nöllenburg, Meirav Zehavi, and Liana Khazaliya. New Frontiers of Parameterized Complexity in Graph Drawing (Dagstuhl Seminar 23162). In Dagstuhl Reports, Volume 13, Issue 4, pp. 58-97, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@Article{ganian_et_al:DagRep.13.4.58,
  author =	{Ganian, Robert and Montecchiani, Fabrizio and N\"{o}llenburg, Martin and Zehavi, Meirav and Khazaliya, Liana},
  title =	{{New Frontiers of Parameterized Complexity in Graph Drawing (Dagstuhl Seminar 23162)}},
  pages =	{58--97},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2023},
  volume =	{13},
  number =	{4},
  editor =	{Ganian, Robert and Montecchiani, Fabrizio and N\"{o}llenburg, Martin and Zehavi, Meirav and Khazaliya, Liana},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.13.4.58},
  URN =		{urn:nbn:de:0030-drops-192393},
  doi =		{10.4230/DagRep.13.4.58},
  annote =	{Keywords: algorithm design, computational geometry, graph drawing, parameterized complexity}
}
Document
Learning a Generic Value-Selection Heuristic Inside a Constraint Programming Solver

Authors: Tom Marty, Tristan François, Pierre Tessier, Louis Gautier, Louis-Martin Rousseau, and Quentin Cappart

Published in: LIPIcs, Volume 280, 29th International Conference on Principles and Practice of Constraint Programming (CP 2023)


Abstract
Constraint programming is known for being an efficient approach to solving combinatorial problems. Important design choices in a solver are the branching heuristics, designed to lead the search to the best solutions in a minimum amount of time. However, developing these heuristics is a time-consuming process that requires problem-specific expertise. This observation has motivated many efforts to use machine learning to automatically learn efficient heuristics without expert intervention. Although several generic variable-selection heuristics are available in the literature, the options for value-selection heuristics are more scarce. We propose to tackle this issue by introducing a generic learning procedure that can be used to obtain a value-selection heuristic inside a constraint programming solver. This has been achieved thanks to the combination of a deep Q-learning algorithm, a tailored reward signal, and a heterogeneous graph neural network. Experiments on graph coloring, maximum independent set, and maximum cut problems show that this framework competes with the well-known impact-based and activity-based search heuristics and can find solutions close to optimality without requiring a large number of backtracks.

Cite as

Tom Marty, Tristan François, Pierre Tessier, Louis Gautier, Louis-Martin Rousseau, and Quentin Cappart. Learning a Generic Value-Selection Heuristic Inside a Constraint Programming Solver. In 29th International Conference on Principles and Practice of Constraint Programming (CP 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 280, pp. 25:1-25:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{marty_et_al:LIPIcs.CP.2023.25,
  author =	{Marty, Tom and Fran\c{c}ois, Tristan and Tessier, Pierre and Gautier, Louis and Rousseau, Louis-Martin and Cappart, Quentin},
  title =	{{Learning a Generic Value-Selection Heuristic Inside a Constraint Programming Solver}},
  booktitle =	{29th International Conference on Principles and Practice of Constraint Programming (CP 2023)},
  pages =	{25:1--25:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-300-3},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{280},
  editor =	{Yap, Roland H. C.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2023.25},
  URN =		{urn:nbn:de:0030-drops-190625},
  doi =		{10.4230/LIPIcs.CP.2023.25},
  annote =	{Keywords: Branching heuristic, Deep reinforcement learning}
}
Document
Sorting Finite Automata via Partition Refinement

Authors: Ruben Becker, Manuel Cáceres, Davide Cenzato, Sung-Hwan Kim, Bojana Kodric, Francisco Olivares, and Nicola Prezza

Published in: LIPIcs, Volume 274, 31st Annual European Symposium on Algorithms (ESA 2023)


Abstract
Wheeler nondeterministic finite automata (WNFAs) were introduced in (Gagie et al., TCS 2017) as a powerful generalization of prefix sorting from strings to labeled graphs. WNFAs admit optimal solutions to classic hard problems on labeled graphs and languages such as compression and regular expression matching. The problem of deciding whether a given NFA is Wheeler is known to be NP-complete (Gibney and Thankachan, ESA 2019). Recently, however, Alanko et al. (Information and Computation 2021) showed how to side-step this complexity by switching to preorders: letting Q be the set of states and δ the set of transitions, they provided a O(|δ|⋅|Q|²)-time algorithm computing a totally-ordered partition (i.e. equivalence relation) of the WNFA’s states such that (1) equivalent states recognize the same regular language, and (2) the order of (the classes of) non-equivalent states is consistent with any Wheeler order, when one exists. As a result, the output is a preorder of the states as useful for pattern matching as standard Wheeler orders. Further extensions of this line of work (Cotumaccio et al., SODA 2021 and DCC 2022) generalized these concepts to arbitrary NFAs by introducing co-lex partial preorders: in general, any NFA admits a partial preorder of its states reflecting the co-lexicographic order of their accepted strings; the smaller the width of such preorder is, the faster regular expression matching queries can be performed. To date, the fastest algorithm for computing the smallest-width partial preorder on NFAs runs in O(|δ|² + |Q|^{5/2}) time (Cotumaccio, DCC 2022), while on DFAs the same task can be accomplished in O(min(|Q|²log|Q|, |δ|⋅|Q|)) time (Kim et al., CPM 2023). In this paper, we provide much more efficient solutions to the co-lex order computation problem. Our results are achieved by extending a classic algorithm for the relational coarsest partition refinement problem of Paige and Tarjan to work with ordered partitions. More specifically, we provide a O(|δ|log|Q|)-time algorithm computing a co-lex total preorder when the input is a Wheeler NFA, and an algorithm with the same time complexity computing the smallest-width co-lex partial order of any DFA. In addition, we present implementations of our algorithms and show that they are very efficient also in practice.

Cite as

Ruben Becker, Manuel Cáceres, Davide Cenzato, Sung-Hwan Kim, Bojana Kodric, Francisco Olivares, and Nicola Prezza. Sorting Finite Automata via Partition Refinement. In 31st Annual European Symposium on Algorithms (ESA 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 274, pp. 15:1-15:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{becker_et_al:LIPIcs.ESA.2023.15,
  author =	{Becker, Ruben and C\'{a}ceres, Manuel and Cenzato, Davide and Kim, Sung-Hwan and Kodric, Bojana and Olivares, Francisco and Prezza, Nicola},
  title =	{{Sorting Finite Automata via Partition Refinement}},
  booktitle =	{31st Annual European Symposium on Algorithms (ESA 2023)},
  pages =	{15:1--15:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-295-2},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{274},
  editor =	{G{\o}rtz, Inge Li and Farach-Colton, Martin and Puglisi, Simon J. and Herman, Grzegorz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2023.15},
  URN =		{urn:nbn:de:0030-drops-186684},
  doi =		{10.4230/LIPIcs.ESA.2023.15},
  annote =	{Keywords: Wheeler automata, prefix sorting, pattern matching, graph compression, sorting, partition refinement}
}
Document
Space-Efficient Parameterized Algorithms on Graphs of Low Shrubdepth

Authors: Benjamin Bergougnoux, Vera Chekan, Robert Ganian, Mamadou Moustapha Kanté, Matthias Mnich, Sang-il Oum, Michał Pilipczuk, and Erik Jan van Leeuwen

Published in: LIPIcs, Volume 274, 31st Annual European Symposium on Algorithms (ESA 2023)


Abstract
Dynamic programming on various graph decompositions is one of the most fundamental techniques used in parameterized complexity. Unfortunately, even if we consider concepts as simple as path or tree decompositions, such dynamic programming uses space that is exponential in the decomposition’s width, and there are good reasons to believe that this is necessary. However, it has been shown that in graphs of low treedepth it is possible to design algorithms which achieve polynomial space complexity without requiring worse time complexity than their counterparts working on tree decompositions of bounded width. Here, treedepth is a graph parameter that, intuitively speaking, takes into account both the depth and the width of a tree decomposition of the graph, rather than the width alone. Motivated by the above, we consider graphs that admit clique expressions with bounded depth and label count, or equivalently, graphs of low shrubdepth. Here, shrubdepth is a bounded-depth analogue of cliquewidth, in the same way as treedepth is a bounded-depth analogue of treewidth. We show that also in this setting, bounding the depth of the decomposition is a deciding factor for improving the space complexity. More precisely, we prove that on n-vertex graphs equipped with a tree-model (a decomposition notion underlying shrubdepth) of depth d and using k labels, - Independent Set can be solved in time 2^𝒪(dk) ⋅ n^𝒪(1) using 𝒪(dk²log n) space; - Max Cut can be solved in time n^𝒪(dk) using 𝒪(dk log n) space; and - Dominating Set can be solved in time 2^𝒪(dk) ⋅ n^𝒪(1) using n^𝒪(1) space via a randomized algorithm. We also establish a lower bound, conditional on a certain assumption about the complexity of Longest Common Subsequence, which shows that at least in the case of Independent Set the exponent of the parametric factor in the time complexity has to grow with d if one wishes to keep the space complexity polynomial.

Cite as

Benjamin Bergougnoux, Vera Chekan, Robert Ganian, Mamadou Moustapha Kanté, Matthias Mnich, Sang-il Oum, Michał Pilipczuk, and Erik Jan van Leeuwen. Space-Efficient Parameterized Algorithms on Graphs of Low Shrubdepth. In 31st Annual European Symposium on Algorithms (ESA 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 274, pp. 18:1-18:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{bergougnoux_et_al:LIPIcs.ESA.2023.18,
  author =	{Bergougnoux, Benjamin and Chekan, Vera and Ganian, Robert and Kant\'{e}, Mamadou Moustapha and Mnich, Matthias and Oum, Sang-il and Pilipczuk, Micha{\l} and van Leeuwen, Erik Jan},
  title =	{{Space-Efficient Parameterized Algorithms on Graphs of Low Shrubdepth}},
  booktitle =	{31st Annual European Symposium on Algorithms (ESA 2023)},
  pages =	{18:1--18:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-295-2},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{274},
  editor =	{G{\o}rtz, Inge Li and Farach-Colton, Martin and Puglisi, Simon J. and Herman, Grzegorz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2023.18},
  URN =		{urn:nbn:de:0030-drops-186710},
  doi =		{10.4230/LIPIcs.ESA.2023.18},
  annote =	{Keywords: Parameterized complexity, shrubdepth, space complexity, algebraic methods}
}
Document
Introduction
Introduction to the Special Issue on Distributed Hybrid Systems

Authors: Alessandro Abate, Uli Fahrenberg, and Martin Fränzle

Published in: LITES, Volume 8, Issue 2 (2022): Special Issue on Distributed Hybrid Systems. Leibniz Transactions on Embedded Systems, Volume 8, Issue 2


Abstract
This special issue contains seven papers within the broad subject of Distributed Hybrid Systems, that is, systems combining hybrid discrete-continuous state spaces with elements of concurrency and logical or spatial distribution. It follows up on several workshops on the same theme which were held between 2017 and 2019 and organized by the editors of this volume. The first of these workshops was held in Aalborg, Denmark, in August 2017 and associated with the MFCS conference. It featured invited talks by Alessandro Abate, Martin Fränzle, Kim G. Larsen, Martin Raussen, and Rafael Wisniewski. The second workshop was held in Palaiseau, France, in July 2018, with invited talks by Luc Jaulin, Thao Dang, Lisbeth Fajstrup, Emmanuel Ledinot, and André Platzer. The third workshop was held in Amsterdam, The Netherlands, in August 2019, associated with the CONCUR conference. It featured a special theme on distributed robotics and had invited talks by Majid Zamani, Hervé de Forges, and Xavier Urbain. The vision and purpose of the DHS workshops was to connect researchers working in real-time systems, hybrid systems, control theory, formal verification, distributed computing, and concurrency theory, in order to advance the subject of distributed hybrid systems. Such systems are abundant and often safety-critical, but ensuring their correct functioning can in general be challenging. The investigation of their dynamics by analysis tools from the aforementioned domains remains fragmentary, providing the rationale behind the workshops: it was conceived that convergence and interaction of theories, methods, and tools from these different areas was needed in order to advance the subject.

Cite as

LITES, Volume 8, Issue 2: Special Issue on Distributed Hybrid Systems, pp. 0:i-0:iii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@Article{abate_et_al:LITES.8.2.0,
  author =	{Abate, Alessandro and Fahrenberg, Uli and Fr\"{a}nzle, Martin},
  title =	{{Introduction to the Special Issue on Distributed Hybrid Systems}},
  journal =	{Leibniz Transactions on Embedded Systems},
  pages =	{00:1--00:3},
  ISSN =	{2199-2002},
  year =	{2022},
  volume =	{8},
  number =	{2},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LITES.8.2.0},
  doi =		{10.4230/LITES.8.2.0},
  annote =	{Keywords: Distributed hybrid systems}
}
Document
Mobility Data Science (Dagstuhl Seminar 22021)

Authors: Mohamed Mokbel, Mahmoud Sakr, Li Xiong, Andreas Züfle, Jussara Almeida, Taylor Anderson, Walid Aref, Gennady Andrienko, Natalia Andrienko, Yang Cao, Sanjay Chawla, Reynold Cheng, Panos Chrysanthis, Xiqi Fei, Gabriel Ghinita, Anita Graser, Dimitrios Gunopulos, Christian Jensen, Joon-Sook Kim, Kyoung-Sook Kim, Peer Kröger, John Krumm, Johannes Lauer, Amr Magdy, Mario Nascimento, Siva Ravada, Matthias Renz, Dimitris Sacharidis, Cyrus Shahabi, Flora Salim, Mohamed Sarwat, Maxime Schoemans, Bettina Speckmann, Egemen Tanin, Yannis Theodoridis, Kristian Torp, Goce Trajcevski, Marc van Kreveld, Carola Wenk, Martin Werner, Raymond Wong, Song Wu, Jianqiu Xu, Moustafa Youssef, Demetris Zeinalipour, Mengxuan Zhang, and Esteban Zimányi

Published in: Dagstuhl Reports, Volume 12, Issue 1 (2022)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 22021 "Mobility Data Science". This seminar was held January 9-14, 2022, including 47 participants from industry and academia. The goal of this Dagstuhl Seminar was to create a new research community of mobility data science in which the whole is greater than the sum of its parts by bringing together established leaders as well as promising young researchers from all fields related to mobility data science. Specifically, this report summarizes the main results of the seminar by (1) defining Mobility Data Science as a research domain, (2) by sketching its agenda in the coming years, and by (3) building a mobility data science community. (1) Mobility data science is defined as spatiotemporal data that additionally captures the behavior of moving entities (human, vehicle, animal, etc.). To understand, explain, and predict behavior, we note that a strong collaboration with research in behavioral and social sciences is needed. (2) Future research directions for mobility data science described in this report include a) mobility data acquisition and privacy, b) mobility data management and analysis, and c) applications of mobility data science. (3) We identify opportunities towards building a mobility data science community, towards collaborations between academic and industry, and towards a mobility data science curriculum.

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Mohamed Mokbel, Mahmoud Sakr, Li Xiong, Andreas Züfle, Jussara Almeida, Taylor Anderson, Walid Aref, Gennady Andrienko, Natalia Andrienko, Yang Cao, Sanjay Chawla, Reynold Cheng, Panos Chrysanthis, Xiqi Fei, Gabriel Ghinita, Anita Graser, Dimitrios Gunopulos, Christian Jensen, Joon-Sook Kim, Kyoung-Sook Kim, Peer Kröger, John Krumm, Johannes Lauer, Amr Magdy, Mario Nascimento, Siva Ravada, Matthias Renz, Dimitris Sacharidis, Cyrus Shahabi, Flora Salim, Mohamed Sarwat, Maxime Schoemans, Bettina Speckmann, Egemen Tanin, Yannis Theodoridis, Kristian Torp, Goce Trajcevski, Marc van Kreveld, Carola Wenk, Martin Werner, Raymond Wong, Song Wu, Jianqiu Xu, Moustafa Youssef, Demetris Zeinalipour, Mengxuan Zhang, and Esteban Zimányi. Mobility Data Science (Dagstuhl Seminar 22021). In Dagstuhl Reports, Volume 12, Issue 1, pp. 1-34, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@Article{mokbel_et_al:DagRep.12.1.1,
  author =	{Mokbel, Mohamed and Sakr, Mahmoud and Xiong, Li and Z\"{u}fle, Andreas and Almeida, Jussara and Anderson, Taylor and Aref, Walid and Andrienko, Gennady and Andrienko, Natalia and Cao, Yang and Chawla, Sanjay and Cheng, Reynold and Chrysanthis, Panos and Fei, Xiqi and Ghinita, Gabriel and Graser, Anita and Gunopulos, Dimitrios and Jensen, Christian and Kim, Joon-Sook and Kim, Kyoung-Sook and Kr\"{o}ger, Peer and Krumm, John and Lauer, Johannes and Magdy, Amr and Nascimento, Mario and Ravada, Siva and Renz, Matthias and Sacharidis, Dimitris and Shahabi, Cyrus and Salim, Flora and Sarwat, Mohamed and Schoemans, Maxime and Speckmann, Bettina and Tanin, Egemen and Theodoridis, Yannis and Torp, Kristian and Trajcevski, Goce and van Kreveld, Marc and Wenk, Carola and Werner, Martin and Wong, Raymond and Wu, Song and Xu, Jianqiu and Youssef, Moustafa and Zeinalipour, Demetris and Zhang, Mengxuan and Zim\'{a}nyi, Esteban},
  title =	{{Mobility Data Science (Dagstuhl Seminar 22021)}},
  pages =	{1--34},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2022},
  volume =	{12},
  number =	{1},
  editor =	{Mokbel, Mohamed and Sakr, Mahmoud and Xiong, Li and Z\"{u}fle, Andreas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.12.1.1},
  URN =		{urn:nbn:de:0030-drops-169190},
  doi =		{10.4230/DagRep.12.1.1},
  annote =	{Keywords: Spatio-temporal, Tracking, Privacy, Behavior, Data cleaning, Data management, Analytics}
}
Document
Parameterized Complexity in Graph Drawing (Dagstuhl Seminar 21293)

Authors: Robert Ganian, Fabrizio Montecchiani, Martin Nöllenburg, and Meirav Zehavi

Published in: Dagstuhl Reports, Volume 11, Issue 6 (2021)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 21293 "Parameterized Complexity in Graph Drawing". The seminar was held mostly in-person from July 18 to July 23, 2021. It brought together 28 researchers from the Graph Drawing and the Parameterized Complexity research communities with the aim to discuss and explore open research questions on the interface between the two fields. The report collects the abstracts of talks and open problems presented in the seminar, as well as brief progress reports from the working groups.

Cite as

Robert Ganian, Fabrizio Montecchiani, Martin Nöllenburg, and Meirav Zehavi. Parameterized Complexity in Graph Drawing (Dagstuhl Seminar 21293). In Dagstuhl Reports, Volume 11, Issue 6, pp. 82-123, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@Article{ganian_et_al:DagRep.11.6.82,
  author =	{Ganian, Robert and Montecchiani, Fabrizio and N\"{o}llenburg, Martin and Zehavi, Meirav},
  title =	{{Parameterized Complexity in Graph Drawing (Dagstuhl Seminar 21293)}},
  pages =	{82--123},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2021},
  volume =	{11},
  number =	{6},
  editor =	{Ganian, Robert and Montecchiani, Fabrizio and N\"{o}llenburg, Martin and Zehavi, Meirav},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.11.6.82},
  URN =		{urn:nbn:de:0030-drops-155817},
  doi =		{10.4230/DagRep.11.6.82},
  annote =	{Keywords: exact computation, graph algorithms, graph drawing, parameterized complexity}
}
Document
An Efficient, Practical Algorithm and Implementation for Computing Multiplicatively Weighted Voronoi Diagrams

Authors: Martin Held and Stefan de Lorenzo

Published in: LIPIcs, Volume 173, 28th Annual European Symposium on Algorithms (ESA 2020)


Abstract
We present a simple wavefront-like approach for computing multiplicatively weighted Voronoi diagrams of points and straight-line segments in the Euclidean plane. If the input sites may be assumed to be randomly weighted points then the use of a so-called overlay arrangement [Har-Peled & Raichel, Discrete Comput. Geom. 53:547 - 568, 2015] allows to achieve an expected runtime complexity of 𝒪(n log⁴ n), while still maintaining the simplicity of our approach. We implemented the full algorithm for weighted points as input sites, based on CGAL. The results of an experimental evaluation of our implementation suggest 𝒪(n log² n) as a practical bound on the runtime. Our algorithm can be extended to handle also additive weights in addition to multiplicative weights, and it yields a truly simple 𝒪(n log n) solution for solving the one-dimensional version of this problem.

Cite as

Martin Held and Stefan de Lorenzo. An Efficient, Practical Algorithm and Implementation for Computing Multiplicatively Weighted Voronoi Diagrams. In 28th Annual European Symposium on Algorithms (ESA 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 173, pp. 56:1-56:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{held_et_al:LIPIcs.ESA.2020.56,
  author =	{Held, Martin and de Lorenzo, Stefan},
  title =	{{An Efficient, Practical Algorithm and Implementation for Computing Multiplicatively Weighted Voronoi Diagrams}},
  booktitle =	{28th Annual European Symposium on Algorithms (ESA 2020)},
  pages =	{56:1--56:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-162-7},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{173},
  editor =	{Grandoni, Fabrizio and Herman, Grzegorz and Sanders, Peter},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2020.56},
  URN =		{urn:nbn:de:0030-drops-129224},
  doi =		{10.4230/LIPIcs.ESA.2020.56},
  annote =	{Keywords: Voronoi Diagram, multiplicative weight, additive weight, arc expansion, overlay arrangement, implementation, experiments, CGAL, exact arithmetic}
}
Document
On Implementing Straight Skeletons: Challenges and Experiences

Authors: Günther Eder, Martin Held, and Peter Palfrader

Published in: LIPIcs, Volume 164, 36th International Symposium on Computational Geometry (SoCG 2020)


Abstract
We present Cgal implementations of two algorithms for computing straight skeletons in the plane, based on exact arithmetic. One code, named Surfer2, can handle multiplicatively weighted planar straight-line graphs (PSLGs) while our second code, Monos, is specifically targeted at monotone polygons. Both codes are available on GitHub. We discuss algorithmic as well as implementational and engineering details of both codes. Furthermore, we present the results of an extensive performance evaluation in which we compared Surfer2 and Monos to the straight-skeleton package included in Cgal. It is not surprising that our special-purpose code Monos outperforms Cgal’s straight-skeleton implementation. But our tests provide ample evidence that also Surfer2 can be expected to be faster and to consume significantly less memory than the Cgal code. And, of course, Surfer2 is more versatile because it can handle multiplicative weights and general PSLGs as input. Thus, Surfer2 currently is the fastest and most general straight-skeleton code available.

Cite as

Günther Eder, Martin Held, and Peter Palfrader. On Implementing Straight Skeletons: Challenges and Experiences. In 36th International Symposium on Computational Geometry (SoCG 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 164, pp. 38:1-38:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{eder_et_al:LIPIcs.SoCG.2020.38,
  author =	{Eder, G\"{u}nther and Held, Martin and Palfrader, Peter},
  title =	{{On Implementing Straight Skeletons: Challenges and Experiences}},
  booktitle =	{36th International Symposium on Computational Geometry (SoCG 2020)},
  pages =	{38:1--38:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-143-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{164},
  editor =	{Cabello, Sergio and Chen, Danny Z.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2020.38},
  URN =		{urn:nbn:de:0030-drops-121964},
  doi =		{10.4230/LIPIcs.SoCG.2020.38},
  annote =	{Keywords: weighted straight skeleton, implementation, algorithm engineering, experiments, Cgal, Core}
}
Document
Media Exposition
Step-By-Step Straight Skeletons (Media Exposition)

Authors: Günther Eder, Martin Held, and Peter Palfrader

Published in: LIPIcs, Volume 164, 36th International Symposium on Computational Geometry (SoCG 2020)


Abstract
We present two software packages for computing straight skeletons: Monos, our implementation of an algorithm by Biedl et al. (2015), computes the straight skeleton of a monotone input polygon, and Surfer2 implements a generalization of an algorithm by Aichholzer and Aurenhammer (1998) to handle multiplicatively-weighted planar straight-line graphs as input. The graphical user interfaces that ship with our codes support step-by-step computations, where each event can be investigated and studied by the user. This makes them a canonical candidate for educational purposes and detailed event analyses. Both codes are freely available on GitHub.

Cite as

Günther Eder, Martin Held, and Peter Palfrader. Step-By-Step Straight Skeletons (Media Exposition). In 36th International Symposium on Computational Geometry (SoCG 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 164, pp. 76:1-76:4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{eder_et_al:LIPIcs.SoCG.2020.76,
  author =	{Eder, G\"{u}nther and Held, Martin and Palfrader, Peter},
  title =	{{Step-By-Step Straight Skeletons}},
  booktitle =	{36th International Symposium on Computational Geometry (SoCG 2020)},
  pages =	{76:1--76:4},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-143-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{164},
  editor =	{Cabello, Sergio and Chen, Danny Z.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2020.76},
  URN =		{urn:nbn:de:0030-drops-122343},
  doi =		{10.4230/LIPIcs.SoCG.2020.76},
  annote =	{Keywords: weighted straight skeleton, implementation, visualization, graphical user interface, education}
}
Document
CG Challenge
Computing Low-Cost Convex Partitions for Planar Point Sets Based on Tailored Decompositions (CG Challenge)

Authors: Günther Eder, Martin Held, Stefan de Lorenzo, and Peter Palfrader

Published in: LIPIcs, Volume 164, 36th International Symposium on Computational Geometry (SoCG 2020)


Abstract
Our work on minimum convex decompositions is based on two key components: (1) different strategies for computing initial decompositions, partly adapted to the characteristics of the input data, and (2) local optimizations for reducing the number of convex faces of a decomposition. We discuss our main heuristics and show how they helped to reduce the face count.

Cite as

Günther Eder, Martin Held, Stefan de Lorenzo, and Peter Palfrader. Computing Low-Cost Convex Partitions for Planar Point Sets Based on Tailored Decompositions (CG Challenge). In 36th International Symposium on Computational Geometry (SoCG 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 164, pp. 85:1-85:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{eder_et_al:LIPIcs.SoCG.2020.85,
  author =	{Eder, G\"{u}nther and Held, Martin and de Lorenzo, Stefan and Palfrader, Peter},
  title =	{{Computing Low-Cost Convex Partitions for Planar Point Sets Based on Tailored Decompositions}},
  booktitle =	{36th International Symposium on Computational Geometry (SoCG 2020)},
  pages =	{85:1--85:11},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-143-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{164},
  editor =	{Cabello, Sergio and Chen, Danny Z.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2020.85},
  URN =		{urn:nbn:de:0030-drops-122438},
  doi =		{10.4230/LIPIcs.SoCG.2020.85},
  annote =	{Keywords: Computational Geometry, geometric optimization, algorithm engineering, convex decomposition}
}
Document
Design and Analysis of Randomized and Approximation Algorithms (Dagstuhl Seminar 11241)

Authors: Martin Dyer, Uriel Feige, Alan M. Frieze, and Marek Karpinski

Published in: Dagstuhl Reports, Volume 1, Issue 6 (2011)


Abstract
The Dagstuhl Seminar on ``Design and Analysis of Randomized and Approximation Algorithms'' (Seminar 11241) was held at Schloss Dagstuhl between June 13--17, 2011. There were 26 regular talks and several informal and open problem session contributions presented during this seminar. Abstracts of the presentations have been put together in this seminar proceedings document together with some links to extended abstracts and full papers.

Cite as

Martin Dyer, Uriel Feige, Alan M. Frieze, and Marek Karpinski. Design and Analysis of Randomized and Approximation Algorithms (Dagstuhl Seminar 11241). In Dagstuhl Reports, Volume 1, Issue 6, pp. 24-53, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@Article{dyer_et_al:DagRep.1.6.24,
  author =	{Dyer, Martin and Feige, Uriel and Frieze, Alan M. and Karpinski, Marek},
  title =	{{Design and Analysis of Randomized and Approximation Algorithms (Dagstuhl Seminar 11241)}},
  pages =	{24--53},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2011},
  volume =	{1},
  number =	{6},
  editor =	{Dyer, Martin and Feige, Uriel and Frieze, Alan M. and Karpinski, Marek},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.1.6.24},
  URN =		{urn:nbn:de:0030-drops-32585},
  doi =		{10.4230/DagRep.1.6.24},
  annote =	{Keywords: Randomized Algorithms, Approximation Algorithms, Probabilistically Checkable Proofs, Approximation Hardness, Optimization Problems, Counting Problems, Streaming Algorithms, Random Graphs, Hypergraphs, Probabilistic Method, Networks, Linear Programs, Semidefinite Programs}
}
Document
Exploiting graph structure to cope with hard problems (Dagstuhl Seminar 11182)

Authors: Andreas Brandstädt, Martin Charles Golumbic, Pinar Heggernes, and Ross McConnell

Published in: Dagstuhl Reports, Volume 1, Issue 5 (2011)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 11182 ``Exploiting graph structure to cope with hard problems'' which has been held in Schloss Dagstuhl -- Leibniz Center for Informatics from May 1st, 2011 to May 6th, 2011. During the seminar experts with a common focus on graph algorithms presented various new results in how to attack NP-hard graph problems by using the structure of the input graph. Moreover, in the afternoon of each seminar's day new problems have been posed and discussed.

Cite as

Andreas Brandstädt, Martin Charles Golumbic, Pinar Heggernes, and Ross McConnell. Exploiting graph structure to cope with hard problems (Dagstuhl Seminar 11182). In Dagstuhl Reports, Volume 1, Issue 5, pp. 29-46, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@Article{brandstadt_et_al:DagRep.1.5.29,
  author =	{Brandst\"{a}dt, Andreas and Golumbic, Martin Charles and Heggernes, Pinar and McConnell, Ross},
  title =	{{Exploiting graph structure to cope with hard problems (Dagstuhl Seminar 11182)}},
  pages =	{29--46},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2011},
  volume =	{1},
  number =	{5},
  editor =	{Brandst\"{a}dt, Andreas and Golumbic, Martin Charles and Heggernes, Pinar and McConnell, Ross},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.1.5.29},
  URN =		{urn:nbn:de:0030-drops-32027},
  doi =		{10.4230/DagRep.1.5.29},
  annote =	{Keywords: Graph Classes, Graph Algorithms, NP-completeness, Width Parameters, Approximation Algorithms, Parameterized Complexity}
}
Document
10451 Abstracts Collection – Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems

Authors: Klaus Havelund, Martin Leucker, Martin Sachenbacher, Oleg Sokolsky, and Brian C. Williams

Published in: Dagstuhl Seminar Proceedings, Volume 10451, Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems (2011)


Abstract
From November 7 to 12, 2010, the Dagstuhl Seminar 10451 ``Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems'' was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, 35 participants presented their current research and discussed ongoing work and open problems. This document puts together abstracts of the presentations given during the seminar, and provides links to extended abstracts or full papers, if available.

Cite as

Klaus Havelund, Martin Leucker, Martin Sachenbacher, Oleg Sokolsky, and Brian C. Williams. 10451 Abstracts Collection – Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems. In Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems. Dagstuhl Seminar Proceedings, Volume 10451, pp. 1-15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{havelund_et_al:DagSemProc.10451.1,
  author =	{Havelund, Klaus and Leucker, Martin and Sachenbacher, Martin and Sokolsky, Oleg and Williams, Brian C.},
  title =	{{10451 Abstracts Collection – Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems}},
  booktitle =	{Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems},
  pages =	{1--15},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2011},
  volume =	{10451},
  editor =	{Klaus Havelund and Martin Leucker and Martin Sachenbacher and Oleg Sokolsky and Brian C. Williams},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.10451.1},
  URN =		{urn:nbn:de:0030-drops-29487},
  doi =		{10.4230/DagSemProc.10451.1},
  annote =	{Keywords: Runtime Verification, Model-based Diagnosis, Planning, Control, Autonomous Systems}
}
Document
10451 Executive Summary – Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems

Authors: Klaus Havelund, Martin Leucker, Martin Sachenbacher, Oleg Sokolsky, and Brian C. Williams

Published in: Dagstuhl Seminar Proceedings, Volume 10451, Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems (2011)


Abstract
From November 7 to 12, 2010, the Dagstuhl Seminar 10451 'Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems' was held in Schloss Dagstuhl – Leibniz Center for Informatics. During the seminar, 35 participants presented their current research and discussed ongoing work and open problems. This document puts together abstracts of the presentations given during the seminar, and provides links to extended abstracts or full papers, if available.

Cite as

Klaus Havelund, Martin Leucker, Martin Sachenbacher, Oleg Sokolsky, and Brian C. Williams. 10451 Executive Summary – Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems. In Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems. Dagstuhl Seminar Proceedings, Volume 10451, pp. 1-4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)


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@InProceedings{havelund_et_al:DagSemProc.10451.2,
  author =	{Havelund, Klaus and Leucker, Martin and Sachenbacher, Martin and Sokolsky, Oleg and Williams, Brian C.},
  title =	{{10451 Executive Summary – Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems}},
  booktitle =	{Runtime Verification, Diagnosis, Planning and Control for Autonomous Systems},
  pages =	{1--4},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2011},
  volume =	{10451},
  editor =	{Klaus Havelund and Martin Leucker and Martin Sachenbacher and Oleg Sokolsky and Brian C. Williams},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.10451.2},
  URN =		{urn:nbn:de:0030-drops-29476},
  doi =		{10.4230/DagSemProc.10451.2},
  annote =	{Keywords: Runtime Verification, Model-based Diagnosis, Planning, Control, Autonomous Systems}
}
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