6 Search Results for "Weinert, Alexander"


Document
Minimal Obstructions to C₅-Coloring in Hereditary Graph Classes

Authors: Jan Goedgebeur, Jorik Jooken, Karolina Okrasa, Paweł Rzążewski, and Oliver Schaudt

Published in: LIPIcs, Volume 306, 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)


Abstract
For graphs G and H, an H-coloring of G is an edge-preserving mapping from V(G) to V(H). Note that if H is the triangle, then H-colorings are equivalent to 3-colorings. In this paper we are interested in the case that H is the five-vertex cycle C₅. A minimal obstruction to C₅-coloring is a graph that does not have a C₅-coloring, but every proper induced subgraph thereof has a C₅-coloring. In this paper we are interested in minimal obstructions to C₅-coloring in F-free graphs, i.e., graphs that exclude some fixed graph F as an induced subgraph. Let P_t denote the path on t vertices, and let S_{a,b,c} denote the graph obtained from paths P_{a+1},P_{b+1},P_{c+1} by identifying one of their endvertices. We show that there is only a finite number of minimal obstructions to C₅-coloring among F-free graphs, where F ∈ {P₈, S_{2,2,1}, S_{3,1,1}} and explicitly determine all such obstructions. This extends the results of Kamiński and Pstrucha [Discr. Appl. Math. 261, 2019] who proved that there is only a finite number of P₇-free minimal obstructions to C₅-coloring, and of Dębski et al. [ISAAC 2022 Proc.] who showed that the triangle is the unique S_{2,1,1}-free minimal obstruction to C₅-coloring. We complement our results with a construction of an infinite family of minimal obstructions to C₅-coloring, which are simultaneously P_{13}-free and S_{2,2,2}-free. We also discuss infinite families of F-free minimal obstructions to H-coloring for other graphs H.

Cite as

Jan Goedgebeur, Jorik Jooken, Karolina Okrasa, Paweł Rzążewski, and Oliver Schaudt. Minimal Obstructions to C₅-Coloring in Hereditary Graph Classes. In 49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 306, pp. 55:1-55:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{goedgebeur_et_al:LIPIcs.MFCS.2024.55,
  author =	{Goedgebeur, Jan and Jooken, Jorik and Okrasa, Karolina and Rz\k{a}\.{z}ewski, Pawe{\l} and Schaudt, Oliver},
  title =	{{Minimal Obstructions to C₅-Coloring in Hereditary Graph Classes}},
  booktitle =	{49th International Symposium on Mathematical Foundations of Computer Science (MFCS 2024)},
  pages =	{55:1--55:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-335-5},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{306},
  editor =	{Kr\'{a}lovi\v{c}, Rastislav and Ku\v{c}era, Anton{\'\i}n},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2024.55},
  URN =		{urn:nbn:de:0030-drops-206110},
  doi =		{10.4230/LIPIcs.MFCS.2024.55},
  annote =	{Keywords: graph homomorphism, critical graphs, hereditary graph classes}
}
Document
Synthesizing Optimally Resilient Controllers

Authors: Daniel Neider, Alexander Weinert, and Martin Zimmermann

Published in: LIPIcs, Volume 119, 27th EACSL Annual Conference on Computer Science Logic (CSL 2018)


Abstract
Recently, Dallal, Neider, and Tabuada studied a generalization of the classical game-theoretic model used in program synthesis, which additionally accounts for unmodeled intermittent disturbances. In this extended framework, one is interested in computing optimally resilient strategies, i.e., strategies that are resilient against as many disturbances as possible. Dallal, Neider, and Tabuada showed how to compute such strategies for safety specifications. In this work, we compute optimally resilient strategies for a much wider range of winning conditions and show that they do not require more memory than winning strategies in the classical model. Our algorithms only have a polynomial overhead in comparison to the ones computing winning strategies. In particular, for parity conditions optimally resilient strategies are positional and can be computed in quasipolynomial time.

Cite as

Daniel Neider, Alexander Weinert, and Martin Zimmermann. Synthesizing Optimally Resilient Controllers. In 27th EACSL Annual Conference on Computer Science Logic (CSL 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 119, pp. 34:1-34:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{neider_et_al:LIPIcs.CSL.2018.34,
  author =	{Neider, Daniel and Weinert, Alexander and Zimmermann, Martin},
  title =	{{Synthesizing Optimally Resilient Controllers}},
  booktitle =	{27th EACSL Annual Conference on Computer Science Logic (CSL 2018)},
  pages =	{34:1--34:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-088-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{119},
  editor =	{Ghica, Dan R. and Jung, Achim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2018.34},
  URN =		{urn:nbn:de:0030-drops-97010},
  doi =		{10.4230/LIPIcs.CSL.2018.34},
  annote =	{Keywords: Controller Synthesis, Infinite Games, Resilient Strategies, Disturbances}
}
Document
Parity Games with Weights

Authors: Sven Schewe, Alexander Weinert, and Martin Zimmermann

Published in: LIPIcs, Volume 119, 27th EACSL Annual Conference on Computer Science Logic (CSL 2018)


Abstract
Quantitative extensions of parity games have recently attracted significant interest. These extensions include parity games with energy and payoff conditions as well as finitary parity games and their generalization to parity games with costs. Finitary parity games enjoy a special status among these extensions, as they offer a native combination of the qualitative and quantitative aspects in infinite games: the quantitative aspect of finitary parity games is a quality measure for the qualitative aspect, as it measures the limit superior of the time it takes to answer an odd color by a larger even one. Finitary parity games have been extended to parity games with costs, where each transition is labelled with a non-negative weight that reflects the costs incurred by taking it. We lift this restriction and consider parity games with costs with arbitrary integer weights. We show that solving such games is in NP cap co-NP, the signature complexity for games of this type. We also show that the protagonist has finite-state winning strategies, and provide tight exponential bounds for the memory he needs to win the game. Naturally, the antagonist may need infinite memory to win. Finally, we present tight bounds on the quality of winning strategies for the protagonist.

Cite as

Sven Schewe, Alexander Weinert, and Martin Zimmermann. Parity Games with Weights. In 27th EACSL Annual Conference on Computer Science Logic (CSL 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 119, pp. 36:1-36:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{schewe_et_al:LIPIcs.CSL.2018.36,
  author =	{Schewe, Sven and Weinert, Alexander and Zimmermann, Martin},
  title =	{{Parity Games with Weights}},
  booktitle =	{27th EACSL Annual Conference on Computer Science Logic (CSL 2018)},
  pages =	{36:1--36:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-088-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{119},
  editor =	{Ghica, Dan R. and Jung, Achim},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2018.36},
  URN =		{urn:nbn:de:0030-drops-97037},
  doi =		{10.4230/LIPIcs.CSL.2018.36},
  annote =	{Keywords: Infinite Games, Quantitative Games, Parity Games}
}
Document
VLDL Satisfiability and Model Checking via Tree Automata

Authors: Alexander Weinert

Published in: LIPIcs, Volume 93, 37th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2017)


Abstract
We present novel algorithms solving the satisfiability problem and the model checking problem for Visibly Linear Dynamic Logic (VLDL) in asymptotically optimal time via a reduction to the emptiness problem for tree automata with Büchi acceptance. Since VLDL allows for the specification of important properties of recursive systems, this reduction enables the efficient analysis of such systems. Furthermore, as the problem of tree automata emptiness is well-studied, this reduction enables leveraging the mature algorithms and tools for that problem in order to solve the satisfiability problem and the model checking problem for VLDL.

Cite as

Alexander Weinert. VLDL Satisfiability and Model Checking via Tree Automata. In 37th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 93, pp. 47:1-47:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{weinert:LIPIcs.FSTTCS.2017.47,
  author =	{Weinert, Alexander},
  title =	{{VLDL Satisfiability and Model Checking via Tree Automata}},
  booktitle =	{37th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2017)},
  pages =	{47:1--47:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-055-2},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{93},
  editor =	{Lokam, Satya and Ramanujam, R.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2017.47},
  URN =		{urn:nbn:de:0030-drops-83871},
  doi =		{10.4230/LIPIcs.FSTTCS.2017.47},
  annote =	{Keywords: Visibly Linear Dynamic Logic, Visibly Pushdown Languages, Satisfiability, Model Checking, Tree Automata}
}
Document
Visibly Linear Dynamic Logic

Authors: Alexander Weinert and Martin Zimmermann

Published in: LIPIcs, Volume 65, 36th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2016)


Abstract
We introduce Visibly Linear Dynamic Logic (VLDL), which extends Linear Temporal Logic (LTL) by temporal operators that are guarded by visibly pushdown languages over finite words. In VLDL one can, e.g., express that a function resets a variable to its original value after its execution, even in the presence of an unbounded number of intermediate recursive calls. We prove that VLDL describes exactly the omega-visibly pushdown languages. Thus it is strictly more expressive than LTL and able to express recursive properties of programs with unbounded call stacks. The main technical contribution of this work is a translation of VLDL into omega-visibly pushdown automata of exponential size via one-way alternating jumping automata. This translation yields exponential-time algorithms for satisfiability, validity, and model checking. We also show that visibly pushdown games with VLDL winning conditions are solvable in triply-exponential time.We prove all these problems to be complete for their respective complexity classes.

Cite as

Alexander Weinert and Martin Zimmermann. Visibly Linear Dynamic Logic. In 36th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 65, pp. 28:1-28:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{weinert_et_al:LIPIcs.FSTTCS.2016.28,
  author =	{Weinert, Alexander and Zimmermann, Martin},
  title =	{{Visibly Linear Dynamic Logic}},
  booktitle =	{36th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS 2016)},
  pages =	{28:1--28:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-027-9},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{65},
  editor =	{Lal, Akash and Akshay, S. and Saurabh, Saket and Sen, Sandeep},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSTTCS.2016.28},
  URN =		{urn:nbn:de:0030-drops-68639},
  doi =		{10.4230/LIPIcs.FSTTCS.2016.28},
  annote =	{Keywords: Temporal Logic, Visibly Pushdown Languages, Satisfiability, Model Checking, Infinite Games}
}
Document
Easy to Win, Hard to Master: Optimal Strategies in Parity Games with Costs

Authors: Alexander Weinert and Martin Zimmermann

Published in: LIPIcs, Volume 62, 25th EACSL Annual Conference on Computer Science Logic (CSL 2016)


Abstract
The winning condition of a parity game with costs requires an arbitrary, but fixed bound on the distance between occurrences of odd colors and the next occurrence of a larger even one. Such games quantitatively extend parity games while retaining most of their attractive properties, i.e, determining the winner is in NP and co-NP and one player has positional winning strategies. We show that the characteristics of parity games with costs are vastly different when asking for strategies realizing the minimal such bound: the solution problem becomes PSPACE-complete and exponential memory is both necessary in general and always sufficient. Thus, playing parity games with costs optimally is harder than just winning them. Moreover, we show that the tradeoff between the memory size and the realized bound is gradual in general.

Cite as

Alexander Weinert and Martin Zimmermann. Easy to Win, Hard to Master: Optimal Strategies in Parity Games with Costs. In 25th EACSL Annual Conference on Computer Science Logic (CSL 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 62, pp. 31:1-31:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@InProceedings{weinert_et_al:LIPIcs.CSL.2016.31,
  author =	{Weinert, Alexander and Zimmermann, Martin},
  title =	{{Easy to Win, Hard to Master: Optimal Strategies in Parity Games with Costs}},
  booktitle =	{25th EACSL Annual Conference on Computer Science Logic (CSL 2016)},
  pages =	{31:1--31:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-022-4},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{62},
  editor =	{Talbot, Jean-Marc and Regnier, Laurent},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CSL.2016.31},
  URN =		{urn:nbn:de:0030-drops-65714},
  doi =		{10.4230/LIPIcs.CSL.2016.31},
  annote =	{Keywords: Parity Games with Costs, Optimal Strategies, Memory Requirements, Tradeoffs}
}
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