Sebastian Siebertz

Professor Sebastian Siebertz is a faculty member in the Department of Computer Science at the Faculty of Mathematics and Computer Science, University of Bremen. His research focuses on the intersection of graph theory and logic in computer science, particularly in the areas of sparse graph classes and algorithmic meta-theorems.

His primary research interests include Algorithmic Graph Structure Theory (especially sparse and structurally sparse graphs), Logic in Computer Science (particularly first-order model-checking, query evaluation, enumeration, and counting), and Applications of stability theory in the finite. He has made significant contributions to the theory of bounded expansion and nowhere dense graph classes, which provide robust notions of uniform sparsity. Notably, in collaboration with Martin Grohe and Stephan Kreutzer, he proved that the first-order model-checking problem is fixed-parameter tractable on nowhere dense graph classes.

His recent publications (2022-2024) demonstrate a strong focus on extending model-checking results to more general graph classes, exploring connections with stability theory, and developing efficient algorithms for graph problems, particularly in reconfiguration, connectivity, and structural graph theory.

Professor Siebertz actively serves the academic community through program committee memberships for major conferences including LICS, IPEC, and Highlights of Logics, Games and Automata, and has organized Dagstuhl seminars on sparsity in algorithms, combinatorics and logic.

He currently supervises several doctoral students and postdocs, including Dr. Alexandre Vigny, Mario Grobler, and Nikolas Mählmann, indicating an active research group focused on theoretical computer science problems at the University of Bremen.