## Dr. Stefan Witzel

Note: I've moved to Bielefeld University. My new website can be found here.

Mathematisches Institut

Universität Münster

Einsteinstraße 62

48149 Münster

Office: 304

Phone: +49 (251) 83 33739

Fax: +49 (251) 83 33712

Email: s.witzel [at] uni-muenster.de

### Research interests

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

### Publications and preprints

Publications

- Stefan Witzel,
*Finiteness Properties of Chevalley Groups over the Ring of (Laurent) Polynomials over a Finite Field*, Dissertation, TU Darmstadt, Supervisors: Prof. Ralf Gramlich, Prof. Kai-Uwe Bux. - Ralf Köhl and Stefan Witzel,
*The sphericity of the Phan geometries of type B*, Transactions of the AMS, 365 (2013), 1577-1602, arXiv:0901.1156._{n}and C_{n}and the Phan-type theorem of type F_{4} - 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. - Stefan Witzel,
*Abels's groups revisited*, Algebraic & Geometric Topology, 13 (2013), 3447-3467, arXiv:1206.0977. - Martin Fluch, Marco Schwandt, Stefan Witzel, and Matthew C. B. Zaremsky,
*The Brin-Thompson groups sV are of type F*, Pacific Journal of Mathematics, 266 (2013), 283-295, arXiv:1207.4832._{∞} - Martin Fluch and Stefan Witzel,
*Brown's criterion in Bredon homology*, Homology, Homotopy and Applications, 15 (2013), 153-162, arXiv:1206.0962. - Kai-Uwe Bux, Martin Fluch, Marco Schwandt, Stefan Witzel, and Matthew C. B. Zaremsky,
*The braided Thompson's groups are of type F*, to appear in Journal für die reine und angewandte Mathematik (Crelle's journal), arXiv:1210.2931._{∞}

Preprints

- Stefan Witzel and Matthew C. B. Zaremsky,
*A free subgroup in the image of the 4-strand Burau representation*, arXiv:1304.7923. - Kim Ruane and Stefan Witzel,
*CAT(0) cubical complexes for graph products of finitely generated abelian groups*, arXiv:1310.8646. - Stefan Witzel and Matthew C. B. Zaremsky,
*Thompson groups for systems of groups, and their finiteness properties*, arXiv:1405.5491.

Unpublished manuscripts

- Matthew C. B. Zaremsky und Stefan Witzel,
*Thompson groups for systems of groups, and their finiteness properties*, preliminary version. - 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.

### Grants

- from July 2014, “Temporary Position for Principal Investigator” from DFG

### Selected talks

Conference talks

- 15 October 2013,
*Proper finiteness properties of certain solvable arithmetic groups*, Classifying spaces, loop spaces and finiteness, University of Copenhagen. - 13 August 2013,
*Classifying spaces for families of subgroups and their finiteness properties*, Geometric and Cohomological Group Theory, EPSRC Durham Symposium. - 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.

### Teaching

- 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.