Research Group Geometry, Topology and Group theory

Dr. Stefan Witzel

Office: 304
Phone: +49 (251) 83 33739
Fax: +49 (251) 83 33712
Email: s.witzel [at] uni-muenster.de

Geometric group theory, buildings, combinatorial topology, arithmetic groups, lattices in locally compact groups

Stefan Witzel, Dissertation, Finiteness Properties of Chevalley Groups over the Ring of (Laurent) Polynomials over a Finite Field, TU Darmstadt, Supervisors: Prof. Ralf Gramlich, Prof. Kai-Uwe Bux.
Ralf Köhl and Stefan Witzel, The sphericity of the Phan geometries of type B_n and C_n and the Phan-type theorem of type F₄, Transactions of the AMS, 365 (2013), 1577-1602, arXiv:0901.1156.
Kai-Uwe Bux, Ralf Gramlich, and Stefan Witzel, Higher finiteness properties of reductive arithmetic groups in positive characteristic: The Rank Theorem, Annals of Mathematics, 177 (2013), 311-366, arXiv:1102.0428.
Martin Fluch, Marco Schwandt, Stefan Witzel, and Matthew C. B. Zaremsky, The Brin-Thompson groups sV are of type F_∞, to appear in Pacific Journal of Mathematics, arxiv:1207.4832.
Stefan Witzel, Abels's groups revisited, to appear in Algebraic & Geometric Topology, arXiv:1206.0977.
Martin Fluch and Stefan Witzel, Brown's criterion in Bredon homology, to appear in Homology, Homotopy and Applications, arXiv:1206.0962.

Preprints

Kai-Uwe Bux, Martin Fluch, Marco Schwandt, Stefan Witzel, and Matthew C. B. Zaremsky, The braided Thompson's groups are of type F_∞, arxiv:1210.2931.
Stefan Witzel, Matthew C. B. Zaremsky, A free subgroup in the image of the 4-strand Burau representation, arxiv:1304.7923.

Unpublished manuscripts

Kai-Uwe Bux, Ralf Gramlich, and Stefan Witzel, Finiteness properties of Chevalley Groups over a Polynomial Ring over a Finite Field, arXiv:0908.4531.
Stefan Witzel, Finiteness Properties of Chevalley Groups over the Laurent Polynomial Ring over a Finite Field, arXiv:1007.5216.
Kai-Uwe Bux and Stefan Witzel, Local convexity in CAT(κ)-spaces, arXiv:1211.1871.

Conference talks

15 April 2013, Proper finiteness properties of some solvable arithmetic groups in positive characteristic, Arithmetic Groups, BIRS, Banff, Alberta.
2 October 2012, Generalizations of Abels's groups and their Bredon-finiteness properties, Buildings 2012, Münster University.
20 June 2012, Finiteness properties of S-arithmetic groups, Journées Solstice d'été, Paris.
17 February 2012, Cocompact actions for arithmetic groups, Groups and Geometry in the South East, Oxford.
5 November 2011, Einfach zusammenhängende Geometrien und Präsentierungen von Gruppen, Norddeutsches Gruppentheorie Kolloquium, Gießen University.
4 October 2011, Some convex subsets of Euclidean buildings, Buildings 2011, Münster University.
19 July 2011, Finiteness properties of S-arithmetic groups, Geometric presentations of finite and infinite groups, University of Birmingham.
30 April 2011, Finiteness properties of S-arithmetic groups, Buildings, automorphisms of RAAGs, and outer space, Ohio State University, Columbus.
4 October 2010, Finiteness properties of S-arithmetic groups, Buildings 2010, Münster University.

Seminar talks

19 February 2013, Finiteness properties of arithmetic groups in positive characteristic, Universität Paderborn.
18 January 2013, Finiteness properties of arithmetic groups in positive characteristic, Université Claude Bernard Lyon 1.
14 November 2012, Finiteness properties of Thompson's groups, Gießen University.
29 June 2012, Harder's reduction theory and the Rank Theorem, Tufts University, Boston.
20 March 2012, Bredon-finiteness properties of Abels's groups, Bielefeld University.
15 February 2012, Groups with prescribed finiteness properties, University of Oxford.
25 January 2012, Brown's Criterion by Example, Bielefeld University.
28 April 2009, Finiteness properties of unitary forms of Kac-Moody groups, University of Virginia, Charlottesville.

ST 2013, Seminar Groups and nonpositive curvature, WWU Münster, with Petra Schwer.
ST 2012, Seminar Gruppentheorie und Topologie, WWU Münster, with Linus Kramer, Daniel Skodlerack, and Olga Varghese.
ST 2011, Exercises for the course Gruppentheorie, WWU Münster, with Daniel Skodlerack and Olga Varghese.
ST 2010, Seminar lokalkompakte Gruppen, TU Darmstadt, with Ralf Gramlich.