@article{Bang‐JensenBellittoSchweseretal.2019, author = {Bang-Jensen, J{\o}rgen and Bellitto, Thomas and Schweser, Thomas and Stiebitz, Michael}, title = {On DP-coloring of digraphs}, series = {Journal of Graph Theory}, volume = {95}, journal = {Journal of Graph Theory}, number = {1}, publisher = {Wiley}, issn = {0364-9024}, doi = {10.1002/jgt.22535}, pages = {76 -- 98}, year = {2019}, abstract = {DP-coloring is a relatively new coloring concept by Dvoř{\´a}k and Postle and was introduced as an extension of list-colorings of (undirected) graphs. It transforms the problem of finding a list-coloring of a given graph with a list-assignment to finding an independent transversal in an auxiliary graph with vertex set . In this paper, we extend the definition of DP-colorings to digraphs using the approach from Neumann-Lara where a coloring of a digraph is a coloring of the vertices such that the digraph does not contain any monochromatic directed cycle. Furthermore, we prove a Brooks' type theorem regarding the DP-chromatic number, which extends various results on the (list-)chromatic number of digraphs.}, language = {en} } @article{BangJensenBellittoSchweseretal.2020, author = {Bang-Jensen, J{\o}rgen and Bellitto, Thomas and Schweser, Thomas and Stiebitz, Michael}, title = {Haj{\´o}s and Ore Constructions for Digraphs}, series = {The Electronic Journal of Combinatorics}, volume = {27}, journal = {The Electronic Journal of Combinatorics}, number = {1}, publisher = {The Electronic Journal of Combinatorics}, issn = {1077-8926}, doi = {10.37236/8942}, year = {2020}, language = {en} } @article{KostochkaSchweserStiebitz2023, author = {Kostochka, Alexandr V. and Schweser, Thomas and Stiebitz, Michael}, title = {Generalized DP-colorings of graphs}, series = {Discrete Mathematics}, volume = {346}, journal = {Discrete Mathematics}, number = {11}, publisher = {Elsevier BV}, issn = {0012-365X}, doi = {10.1016/j.disc.2022.113186}, pages = {20}, year = {2023}, abstract = {In the present paper we extend the following three coloring concepts for the class of finite undirected graphs having multiple edges but no loops. First of all, the generalized coloring concept, in which the same colored vertices of a graph induce a subgraph satisfying a prescribed graph property. Secondly, the concept of variable degeneracy, which was introduced by Borodin, Kostochka and Toft in 2000; this makes it possible to give a common generalization of the point partition number and the list chromatic number. Finally, the DP-coloring concept as introduced by Ďvor{\´a}k and Postle in 2018, where a list assignment of a graph is replaced by a cover. Combining these three coloring concepts leads to generalizations of various classical coloring results, including the theorems of Brooks, of Gallai, and of Erdős, Rubin and Taylor. Our main result is a DP-version of a theorem about partitions of graphs into a fixed number of induced subgraphs with bounded variable degeneracy due to Borodin, Kostochka, and Toft.}, language = {en} } @article{vonPostelSchweserStiebitz2022, author = {von Postel, Justus and Schweser, Thomas and Stiebitz, Michael}, title = {Point partition numbers: Decomposable and indecomposable critical graphs}, series = {Discrete Mathematics}, volume = {345}, journal = {Discrete Mathematics}, number = {8}, publisher = {Elsevier BV}, issn = {0012-365X}, doi = {10.1016/j.disc.2022.112903}, year = {2022}, abstract = {In the present paper we extend the following three coloring concepts for the class of finite undirected graphs having multiple edges but no loops. First of all, the generalized coloring concept, in which the same colored vertices of a graph induce a subgraph satisfying a prescribed graph property. Secondly, the concept of variable degeneracy, which was introduced by Borodin, Kostochka and Toft in 2000; this makes it possible to give a common generalization of the point partition number and the list chromatic number. Finally, the DP-coloring concept as introduced by Ďvor{\´a}k and Postle in 2018, where a list assignment of a graph is replaced by a cover. Combining these three coloring concepts leads to generalizations of various classical coloring results, including the theorems of Brooks, of Gallai, and of Erdős, Rubin and Taylor. Our main result is a DP-version of a theorem about partitions of graphs into a fixed number of induced subgraphs with bounded variable degeneracy due to Borodin, Kostochka, and Toft.}, language = {en} } @article{vonPostelSchweserStiebitz2022, author = {von Postel, Justus and Schweser, Thomas and Stiebitz, Michael}, title = {Point Partition Numbers: Perfect Graphs}, series = {Graphs and Combinatorics}, volume = {38}, journal = {Graphs and Combinatorics}, number = {2}, publisher = {Springer Science and Business Media LLC}, issn = {0911-0119}, doi = {10.1007/s00373-021-02410-w}, pages = {11}, year = {2022}, language = {en} } @article{SchweserStiebitz2020, author = {Schweser, Thomas and Stiebitz, Michael}, title = {Partitions of hypergraphs under variable degeneracy constraints}, series = {Journal of Graph Theory}, volume = {96}, journal = {Journal of Graph Theory}, number = {1}, publisher = {Wiley}, issn = {0364-9024}, doi = {https://doi.org/10.1002/jgt.22575}, pages = {7 -- 33}, year = {2020}, abstract = {The paper deals with partitions of hypergraphs into induced subhypergraphs satisfying constraints on their degeneracy. Our hypergraphs may have multiple edges, but no loops. Given a hypergraph and a sequence of vertex functions such that for all , we want to find a sequence of vertex disjoint induced subhypergraphs containing all vertices of such that each hypergraph is strictly -degenerate, that is, for every nonempty subhypergraph there is a vertex such that . Our main result in this paper says that such a sequence of hypergraphs exists if and only if is not a so-called hard pair. Hard pairs form a recursively defined family of configurations, obtained from three basic types of configurations by the operation of merging a vertex. Our main result has several interesting applications related to generalized hypergraph coloring problems.}, language = {en} } @article{BangJensenSchweserStiebitz2022, author = {Bang-Jensen, J{\o}rgen and Schweser, Thomas and Stiebitz, Michael}, title = {Digraphs and Variable Degeneracy}, series = {SIAM Journal on Discrete Mathematics}, volume = {36}, journal = {SIAM Journal on Discrete Mathematics}, number = {1}, publisher = {Society for Industrial \& Applied Mathematics (SIAM)}, issn = {0895-4801}, doi = {10.1137/20M1386827}, pages = {578 -- 595}, year = {2022}, language = {en} } @article{Schweser2021, author = {Schweser, Thomas}, title = {Generalized hypergraph coloring}, series = {Discussiones Mathematicae Graph Theory}, volume = {41}, journal = {Discussiones Mathematicae Graph Theory}, number = {1}, doi = {10.7151/dmgt.2168}, pages = {103 -- 121}, year = {2021}, language = {en} } @article{Schweser2019, author = {Schweser, Thomas}, title = {DP-degree colorable hypergraphs}, series = {Theoretical Computer Science}, volume = {796}, journal = {Theoretical Computer Science}, publisher = {Elsevier BV}, issn = {0304-3975}, doi = {10.1016/j.tcs.2019.09.010}, pages = {196 -- 206}, year = {2019}, language = {en} } @article{SchweserStiebitz2019, author = {Schweser, Thomas and Stiebitz, Michael}, title = {Partitions of multigraphs under minimum degree constraints}, series = {Discrete Applied Mathematics}, volume = {257}, journal = {Discrete Applied Mathematics}, publisher = {Elsevier BV}, issn = {0166-218X}, doi = {10.1016/j.dam.2018.10.016}, pages = {269 -- 275}, year = {2019}, language = {en} } @article{SchweserStiebitz2017, author = {Schweser, Thomas and Stiebitz, Michael}, title = {Degree choosable signed graphs}, series = {Discrete Mathematics}, volume = {340}, journal = {Discrete Mathematics}, number = {5}, publisher = {Elsevier BV}, issn = {0012-365X}, doi = {10.1016/j.disc.2017.01.007}, pages = {882 -- 891}, year = {2017}, language = {en} } @book{StiebitzSchweserToft2024, author = {Stiebitz, Michael and Schweser, Thomas and Toft, Bjarne}, title = {Brooks' Theorem}, series = {Springer Monographs in Mathematics}, journal = {Springer Monographs in Mathematics}, publisher = {Springer Nature Switzerland}, isbn = {9783031500640}, doi = {10.1007/978-3-031-50065-7}, pages = {655}, year = {2024}, language = {en} } @misc{KlaebeHagedornGropengiesseretal.2025, author = {Kl{\"a}be, Steffen and Hagedorn, Stefan and Gropengießer, Francis and Schweser, Thomas}, title = {Beyond the Data Warehouse: Modern and fast Data Analytics in Actian Vector.}, series = {Datenbanksysteme f{\"u}r Business, Technologie und Web (BTW 2025)}, journal = {Datenbanksysteme f{\"u}r Business, Technologie und Web (BTW 2025)}, doi = {10.18420/BTW2025-35}, pages = {691 -- 697}, year = {2025}, abstract = {Modern data analytics cover a wide range of tools and frameworks besides traditional SQL-based analytics, leading to the need to transform traditional data warehouse solutions into data platforms. In this paper we focus on ecosystem integration, query performance and ease-of-use as key differentiators. We spotlight capabilities we introduced into our analytical database system Actian Vector with respect to these differentiators and highlight challenges we faced when applying research ideas to a production-ready system. The described capabilities cover ecosystem integrations with Apache Spark and a containerized services framework, cost model optimizations for robust query planning and several features to improve usability and manageability of the system.}, language = {en} } @misc{JunkerNaumerSchweseretal.2025, author = {Junker, Elmar and Naumer, Birgit and Schweser, Thomas and Deschle-Prill, Silke and Kraus, Nicole and Lackovic, Josip and Lux, Christine and Sanewski, Anne}, title = {Reduzierte MINT-Durchfallraten durch KI:}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:861-opus4-32848}, year = {2025}, language = {de} }