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Documents authored by Schneider, Thomas

Document
Track A: Algorithms, Complexity and Games
DOI: 10.4230/LIPIcs.ICALP.2025.129
An Upper Bound on the Weisfeiler-Leman Dimension

Authors: Thomas Schneider and Pascal Schweitzer

Published in: LIPIcs, Volume 334, 52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)

Abstract
The Weisfeiler-Leman (WL) algorithms form a family of incomplete approaches to the graph isomorphism problem. They recently found various applications in algorithmic group theory and machine learning. In fact, the algorithms form a parameterized family: for each k ∈ ℕ there is a corresponding k-dimensional algorithm WLk. The algorithms become increasingly powerful with increasing dimension, but at the same time the running time increases. The WL-dimension of a graph G is the smallest k ∈ ℕ for which WLk correctly decides isomorphism between G and every other graph. In some sense, the WL-dimension measures how difficult it is to test isomorphism of one graph to others using a fairly general class of combinatorial algorithms. Nowadays, it is a standard measure in descriptive complexity theory for the structural complexity of a graph. We prove that the WL-dimension of a graph on n vertices is at most 3/20 ⋅ n + o(n) = 0.15 ⋅ n + o(n). Reducing the question to coherent configurations, the proof develops various techniques to analyze their structure. This includes sufficient conditions under which a fiber can be restored uniquely up to isomorphism if it is removed, a recursive proof exploiting a degree reduction and treewidth bounds, as well as an exhaustive analysis of interspaces involving small fibers. As a base case, we also analyze the dimension of coherent configurations with small fiber size and thereby graphs with small color class size.
Cite as

Thomas Schneider and Pascal Schweitzer. An Upper Bound on the Weisfeiler-Leman Dimension. In 52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 334, pp. 129:1-129:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{schneider_et_al:LIPIcs.ICALP.2025.129,
  author =	{Schneider, Thomas and Schweitzer, Pascal},
  title =	{{An Upper Bound on the Weisfeiler-Leman Dimension}},
  booktitle =	{52nd International Colloquium on Automata, Languages, and Programming (ICALP 2025)},
  pages =	{129:1--129:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-372-0},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{334},
  editor =	{Censor-Hillel, Keren and Grandoni, Fabrizio and Ouaknine, Jo\"{e}l and Puppis, Gabriele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2025.129},
  URN =		{urn:nbn:de:0030-drops-235065},
  doi =		{10.4230/LIPIcs.ICALP.2025.129},
  annote =	{Keywords: Weisfeiler-Leman dimension, descriptive complexity, coherent configurations}
}
Document
Short Paper
DOI: 10.4230/LIPIcs.COSIT.2019.28
Granular Spatial Calculi of Relative Directions or Movements with Parallelism: Consistent Account (Short Paper)

Authors: Reinhard Moratz, Leif Sabellek, and Thomas Schneider

Published in: LIPIcs, Volume 142, 14th International Conference on Spatial Information Theory (COSIT 2019)

Abstract
The OPRA* calculus family, originally suggested by Frank Dylla, adds parallelism to the OPRA calculus family which is very popular in Qualitative Spatio-temporal Reasoning (QSTR). Adding parallelism enables the direct representation of parallel moving objects, which is relevant in many applications like traffic monitoring. However, it turned out that it is hard to derive a sound geometric analysis. So far no sound spatial reasoning was supported. Our new generic analysis based on combining condensed semantics lower bounds with upper bounds from algebraic mappings of related calculi already leads to a close and sound approximization. This approximization can be easily augmented with a manual analysis of few geometrically underconstrained cases and then yields a complete analysis of possible configurations in this oriented point framework. This for the first time enables sound standard QSTR constraint reasoning for the OPRA* calculus family.
Cite as

Reinhard Moratz, Leif Sabellek, and Thomas Schneider. Granular Spatial Calculi of Relative Directions or Movements with Parallelism: Consistent Account (Short Paper). In 14th International Conference on Spatial Information Theory (COSIT 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 142, pp. 28:1-28:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{moratz_et_al:LIPIcs.COSIT.2019.28,
  author =	{Moratz, Reinhard and Sabellek, Leif and Schneider, Thomas},
  title =	{{Granular Spatial Calculi of Relative Directions or Movements with Parallelism: Consistent Account}},
  booktitle =	{14th International Conference on Spatial Information Theory (COSIT 2019)},
  pages =	{28:1--28:9},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-115-3},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{142},
  editor =	{Timpf, Sabine and Schlieder, Christoph and Kattenbeck, Markus and Ludwig, Bernd and Stewart, Kathleen},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.COSIT.2019.28},
  URN =		{urn:nbn:de:0030-drops-111206},
  doi =		{10.4230/LIPIcs.COSIT.2019.28},
  annote =	{Keywords: qualitative spatial-temporal reasoning, composition table, condensed semantics, homomorphic embeddings}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2018.15
Querying the Unary Negation Fragment with Regular Path Expressions

Authors: Jean Christoph Jung, Carsten Lutz, Mauricio Martel, and Thomas Schneider

Published in: LIPIcs, Volume 98, 21st International Conference on Database Theory (ICDT 2018)

Abstract
The unary negation fragment of first-order logic (UNFO) has recently been proposed as a generalization of modal logic that shares many of its good computational and model-theoretic properties. It is attractive from the perspective of database theory because it can express conjunctive queries (CQs) and ontologies formulated in many description logics (DLs). Both are relevant for ontology-mediated querying and, in fact, CQ evaluation under UNFO ontologies (and thus also under DL ontologies) can be `expressed' in UNFO as a satisfiability problem. In this paper, we consider the natural extension of UNFO with regular expressions on binary relations. The resulting logic UNFOreg can express (unions of) conjunctive two-way regular path queries (C2RPQs) and ontologies formulated in DLs that include transitive roles and regular expressions on roles. Our main results are that evaluating C2RPQs under UNFOreg ontologies is decidable, 2ExpTime-complete in combined complexity, and coNP-complete in data complexity, and that satisfiability in UNFOreg is 2ExpTime-complete, thus not harder than in UNFO.
Cite as

Jean Christoph Jung, Carsten Lutz, Mauricio Martel, and Thomas Schneider. Querying the Unary Negation Fragment with Regular Path Expressions. In 21st International Conference on Database Theory (ICDT 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 98, pp. 15:1-15:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)

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@InProceedings{jung_et_al:LIPIcs.ICDT.2018.15,
  author =	{Jung, Jean Christoph and Lutz, Carsten and Martel, Mauricio and Schneider, Thomas},
  title =	{{Querying the Unary Negation Fragment with Regular Path Expressions}},
  booktitle =	{21st International Conference on Database Theory (ICDT 2018)},
  pages =	{15:1--15:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-063-7},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{98},
  editor =	{Kimelfeld, Benny and Amsterdamer, Yael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2018.15},
  URN =		{urn:nbn:de:0030-drops-85971},
  doi =		{10.4230/LIPIcs.ICDT.2018.15},
  annote =	{Keywords: Query Answering, Regular Path Queries, Decidable Fragments of First-Order Logic, Computational Complexity}
}
Document
Complete Volume
DOI: 10.4230/LIPIcs.TIME.2017
LIPIcs, Volume 90, TIME'17, Complete Volume

Authors: Sven Schewe, Thomas Schneider, and Jef Wijsen

Published in: LIPIcs, Volume 90, 24th International Symposium on Temporal Representation and Reasoning (TIME 2017)

Abstract
LIPIcs, Volume 90, TIME'17, Complete Volume
Cite as

24th International Symposium on Temporal Representation and Reasoning (TIME 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 90, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@Proceedings{schewe_et_al:LIPIcs.TIME.2017,
  title =	{{LIPIcs, Volume 90, TIME'17, Complete Volume}},
  booktitle =	{24th International Symposium on Temporal Representation and Reasoning (TIME 2017)},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-052-1},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{90},
  editor =	{Schewe, Sven and Schneider, Thomas and Wijsen, Jef},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2017},
  URN =		{urn:nbn:de:0030-drops-80233},
  doi =		{10.4230/LIPIcs.TIME.2017},
  annote =	{Keywords: Distributed Systems, Design Tools and Techniques, Software/Program Verification, Security and Protection, Models of Computation, Specifying and Verifying and Reasoning about Programs, Mathematical Logic, \lbrackNumerical Linear Algebra\rbrack Linear Systems, Graph Theory}
}
Document
Front Matter
DOI: 10.4230/LIPIcs.TIME.2017.0
Front Matter, Table of Contents, Preface, Organization, List of Authors

Authors: Sven Schewe, Thomas Schneider, and Jef Wijsen

Published in: LIPIcs, Volume 90, 24th International Symposium on Temporal Representation and Reasoning (TIME 2017)

Abstract
Front Matter, Table of Contents, Preface, Organization, List of Authors
Cite as

24th International Symposium on Temporal Representation and Reasoning (TIME 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 90, pp. 0:i-0:xiv, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{schewe_et_al:LIPIcs.TIME.2017.0,
  author =	{Schewe, Sven and Schneider, Thomas and Wijsen, Jef},
  title =	{{Front Matter, Table of Contents, Preface, Organization, List of Authors}},
  booktitle =	{24th International Symposium on Temporal Representation and Reasoning (TIME 2017)},
  pages =	{0:i--0:xiv},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-052-1},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{90},
  editor =	{Schewe, Sven and Schneider, Thomas and Wijsen, Jef},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2017.0},
  URN =		{urn:nbn:de:0030-drops-79117},
  doi =		{10.4230/LIPIcs.TIME.2017.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Organization, List of Authors}
}
Document
DOI: 10.4230/LIPIcs.ICALP.2017.108
Conservative Extensions in Guarded and Two-Variable Fragments

Authors: Jean Christoph Jung, Carsten Lutz, Mauricio Martel, Thomas Schneider, and Frank Wolter

Published in: LIPIcs, Volume 80, 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017)

Abstract
We investigate the decidability and computational complexity of (deductive) conservative extensions in fragments of first-order logic (FO), with a focus on the two-variable fragment FO2 and the guarded fragment GF. We prove that conservative extensions are undecidable in any FO fragment that contains FO2 or GF (even the three-variable fragment thereof), and that they are decidable and 2ExpTime-complete in the intersection GF2 of FO2 and GF.
Cite as

Jean Christoph Jung, Carsten Lutz, Mauricio Martel, Thomas Schneider, and Frank Wolter. Conservative Extensions in Guarded and Two-Variable Fragments. In 44th International Colloquium on Automata, Languages, and Programming (ICALP 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 80, pp. 108:1-108:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{jung_et_al:LIPIcs.ICALP.2017.108,
  author =	{Jung, Jean Christoph and Lutz, Carsten and Martel, Mauricio and Schneider, Thomas and Wolter, Frank},
  title =	{{Conservative Extensions in Guarded and Two-Variable Fragments}},
  booktitle =	{44th International Colloquium on Automata, Languages, and Programming (ICALP 2017)},
  pages =	{108:1--108:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-041-5},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{80},
  editor =	{Chatzigiannakis, Ioannis and Indyk, Piotr and Kuhn, Fabian and Muscholl, Anca},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2017.108},
  URN =		{urn:nbn:de:0030-drops-74647},
  doi =		{10.4230/LIPIcs.ICALP.2017.108},
  annote =	{Keywords: Conservative Extensions, Decidable Fragments of First-Order Logic, Computational Complexity\}}
}
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