I am a postdoc in the topology group of the Institute for Algebra and Geometry at KIT. My mathematical interests range around algebraic topology and L²-invariants in geometry and group theory. I am member of the Priority Program 2026 "Geometry at Infinity" and of the RTG 2229 "Asymptotic Invariants and Limits of Groups and Spaces". Here you can find slides of a talk on "The construction of the regular 65.537-gon with compass and straightedge" at the Day of Mathematics 2019 (in German).
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 Dr. Holger Kammeyer |
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Office Hours: nach Vereinbarung Room: 1.007 Phone: +49 (0) 721 608-43707 Fax: +49 (0) 721 608-42148 holger kammeyerCev4∂kit edu |
Karlsruher Institut für Technologie MATH | IAG | AG Topologie Englerstr. 2 | Mathebau (20.30) 76131 Karlsruhe |
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Introduction to ℓ²-invariants
An up-to-date and user-friendly introduction to the rapidly developing field of ℓ ²-invariants.
| Title | Publisher | Year |
|---|---|---|
| Algebraic Topology I | 2016 |
| Title | Coauthors | Year |
|---|---|---|
| Products of free groups in Lie groups | Caterina Campagnolo |
2020 |
| A remark on torsion growth in homology and volume of 3-manifolds | - |
2018 |
| Title | Coauthors | Journal |
|---|---|---|
| Profinite invariants of arithmetic groups | Steffen Kionke, Jean Raimbault, Roman Sauer |
to appear in Forum of Mathematics, Sigma |
| Profinite commensurability of S-arithmetic groups | - |
to appear in Acta Arithmetica |
| S-arithmetic spinor groups with the same finite quotients and distinct L²-cohomology | Roman Sauer |
to appear in Groups, Geometry, and Dynamics. |
| The shrinkage type of knots | - |
Bull. Lond. Math. Soc., 49-3 (2017), 428–442 |
| Approximating Novikov-Shubin numbers of virtually cyclic coverings | - |
Groups, Geometry, and Dynamics, 11-4 (2017), 1231–1251 |
| The Farrell-Jones conjecture for arbitrary lattices in virtually connected Lie groups | Wolfgang Lück, Henrik Rüping |
Geometry & Topology,
20-3 (2016), 1275--1287 |
| L²-invariants of nonuniform lattices in semisimple Lie groups | - |
Algebraic & Geometric Topology, 14 (2014), 2475-2509 |
| An explicit rational structure for real semisimple Lie algebras | - |
Journal of Lie Theory, 24, No. 2 (2014), 307-319 |
| Title | Coauthors | Journal |
|---|---|---|
| From Betti numbers to L²-Betti numbers | Roman Sauer |
to appear in Oberwolfach Snapshots of Modern Mathematics |
| The Heston-Hull-White Model I: Finance and Analytics | Jörg Kienitz |
Wilmott Magazine, |
| Title | Type, University |
|---|---|
| L²-invariants of nonuniform lattices in semisimple Lie groups | doctoral thesis, University of Göttingen |
| On Exotic Manifolds | diploma thesis, University of Göttingen |
Travel
- Arithmetic groups and 3-manifolds
March 2020, Hagen - RTG-Colloquium
Talk: "Profinite properties of lattices in Lie groups"
February 2020, Göttingen - Manifolds and groups
February 2020, Oberwolfach - L2-torsion and symmetric spaces
October 2019, Göttingen - Workshop: Riemannian and Simplicial Volume
April 2019, Karlsruhe - SPP Conference "Geometry at Infinity"
April 2019, Münster - SFB Vorlesung
Talk: "Profinite invariants of arithmetic groups"
November 2018, Regensburg - Growth in Topology and Number Theory: Volume, Entropy, and L2-torsion
Talk: "Profiniteness questions for L2-Betti numbers of S-arithmetic groups"
July 2018, Bonn - L2-invariants and their analogues in positive characteristic
Talk: "Profiniteness questions for L2-Betti numbers of S-arithmetic groups"
June 2018, Madrid, Spain - Joint annual convention GDMV 2018
Talk: "Profinite commensurability of S-arithmetic groups"
March 2018, Paderborn - Nacht der Wissenschaft (Night of Science)
Talk: "Die Konstruktion des regelmäßigen 65.537-Ecks mit Zirkel und Lineal"
November 2017, Karlsruhe - Manifolds and groups
Talk: "Cyclic knot coverings and transcendental numbers"
September 2017, Regensburg - Summer school on "Growth in geometry and topology"
Mini course: "Intro to L2-Betti numbers / L2-torsion and torsion growth in homology"
August 2017, Les Diablerets, Switzerland - Group actions and cohomology in non-positive curvature
June 2017, Cambridge, UK - Groups, manifolds and K-theory
June 2017, Münster - Oberseminar Topologie
Talk: "Secondary L2-invariants of groups and knots"
May 2017, Münster - Compactifications of Buildings and Symmetric Spaces
May 2017, Heidelberg - School on Arithmetic groups
March 2017, Ein Gedi, Israel - Asymptotic geometry of groups and spaces
February 2017, Heidelberg - New directions in L2-invariants
October 2016, Bonn - Oberseminar Topologie
Talk:"L²-invariants of groups and knots"
September 2016, Bonn - Geometry Day
April 2016, Strasbourg, France - Young Geometric Group Theory
February 2016, Karlsruhe - Oberseminar Global Anlaysis
Talk: "Approximating Novikov-Shubin numbers along finite coverings"
January 2016, Regensburg - Geometry day
Talk: "The Farrell-Jones conjecture and lattices in Lie groups"
October 2015, Heidelberg - Topology Retreat
Talk: "Introduction to L²-torsion"
September 2015, Bedlewo, Poland - Manifolds and Groups
September 2015, Ventotene, Italy - Oberseminar Topologie
Talk: "L²-invariants and approximation along finite coverings"
June 2015, Münster - Follow-up workshop to trimester program "Rigidity"
April 2015, Bonn - AG-Seminar Topologie
Talk: "Local rigidity and the Farrell-Jones conjecture"
February 2015, Karlsruhe - Workshop "Geometric Topology"
January 2015, Oberwolfach - Workshop "Topologie"
Short talk: "The Farrell-Jones conjecture for lattices in Lie groups"
September 2014, Oberwolfach - Oberseminar Differentialgeometrie
Talk: "Local rigidity and the Farrell-Jones conjecture"
June 2014, Augsburg - Seminario de Topología Algebraica
Talk: "Rigidez local y la conjetura de Farrell-Jones"
May 2014, Morelia, Mexico - Arbeitsgemeinschaft "Superrigidity"
Talk: "Factor theorems for lattices in products of groups (Bader-Shalom)"
March/April 2014, Oberwolfach - GK-Kolloquium Regensburg
Talk: "L²-invariants and groups"
October 2013, Regensburg - Oberseminar Regensburg
Talk: "Novikov-Shubin numbers of arithmetic groups"
October 2013, Regensburg - Oberseminar Topologie
Talk: "L²-invariants of nonuniform lattices in semisimple Lie groups"
October 2013, Bonn - Geometry, Groups and Topology
October 2013, Karlsruhe - Summer School: Topology of high-dimensional manifolds
August 2013, Bonn - Von Neumann Algebras and Measurable Group Theory
July 2013, Leuven, Belgium - Operator Algebra Seminar
Talk: "On L²-invariants of lattices in semisimple Lie groups"
January 2013, Copenhagen, Denmark - Topology Seminar
Talk: "On L²-invariants of lattices in semisimple Lie groups"
October 2012, Karlsruhe - Workshop "Topologie"
Short talk: "On L²-invariants of lattices in semisimple Lie groups"
September 2012, Oberwolfach - Topology and Groups
June 2012, Berlin - Young Topologists Meeting
Talk: "Compactifications of locally symmetric spaces"
June 2011, Lausanne, Switzerland - Von Neumann algebras and ergodic theory of group actions
April 2011, CIRM Marseille, France - Symplectic and Poisson Geometry in interaction with Algebra, Analysis and Topology
May 2010, MSRI Berkeley, California - Many cheerful facts
Talk: "Fair and unfair prices of financial derivatives"
April 2010, Berkeley, California - Eighth Annual Graduate Student Topology and Geometry Conference
February 2010, Ann Arbor, Michigan - First National Forum of Young Topologists
November 2009, New Orleans, Louisiana - Young Topologists Meeting
Talk: "Classification of 3-sphere bundles over the 4-sphere (Crowley-Escher)"
May 2009, Le Châtelard, Switzerland
Conference: Arithmetic groups and 3-manifolds
| Venue: | In: | Hagen, Germany |
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|---|---|---|---|
| Date: | March, 23rd - 27th, 2020 |
Links: | website |
Workshop "New directions in L2-invariants"
| Venue: | Hausdorff Research Institute for Mathematics |
Place: | Bonn |
|---|---|---|---|
| Date: | 10/04 - 10/07/2016 |
Links: | website |
Junior Trimester Program "Topology"
| Name: | Working group "L2-Invariants" Joint with G. Herrmann, A. Kar, S. Kionke und J. Raimbault. |
Links: | website |
|---|---|---|---|
| Venue: | |||
Summer term 2020
- Lecture "Algebraic Topology" Thu 02:00-03:30 pm, -1.012 UG, Fr 09:45-11:15 am, -1.025 UG
- Seminar "Representation theory of finite groups" block seminar
- RG Seminar "Topology" Thu 03:45-05:15 pm, SR 2.059 (20.30)
Winter term 2019/2020
RG-Seminar "Topology" Thu 03:45-05:15 pm, SR 2.059 (20.30)
Summer term 2019
- Exercise class for Linear Algebra II Fr 02:00 - 03:30 pm, Fritz-Haller-Hörsaal
- RG-Seminar "Topology" Fr 09:45-11:15 am, Raum 2.059 (20.30)
Winter term 2018/2019
- Exercise class for Linear Algebra and Analytic Geometry I Mon 03:45 - 05:15 pm, Carl-Benz-Hörsaal
- RG-Seminar "Topology" Thu 03:45-05:15 pm, 2.058 (20.30)
- Workshop on current developments around the Atiyah conjecture 19.11.18 - 21.11.18
Summer term 2018
- Seminar "Projective Geometry" block course 07/23 - 07/25/2018, SR 0.016 (20.30) seminar announcement
- RG-Seminar "Topology" Thu 03:45-05:15 pm, 2.059 (20.30)
Winter term 2017/2018
- Lecture "Mathematics for Natural Sciences" Tue 08:00-09:30 am, Fr 08:45-09:30 am, 30.46 Chemie Neuer Hörsaal
- RG-Seminar "Topology" Thu 03:45-05:15 pm, 2.058 (20.30)
Summer term 2017
- Seminar: "Differential topology" Thu 09:45-11:15 am, -1.009(UG) (20.30) seminar announcement
- Proseminar: "Proofs from THE BOOK" Thu 02:00-03:30 pm, 2.059 (20.30) proseminar announcement
- RG-Seminar "Arithmetic hyperbolic 3-manifolds" Thu 03:45-05:15 pm 2.059 (20.30) seminar announcement
Winter term 2016/2017
No teaching due to scientific stay in Bonn.
Summer term 2016
- Lecture "Algebraic Topology" Tue 11:30 am-01:00 pm, 2.058 (20.30), Thu 11:30 am-01:00 pm, 0.014 (20.30)
- Tutorial "Algebraic Topology" Wed 05:30-07:00 pm, 2.059 (20.30)
tutor: Jakob Albers - RG-Seminar "Topology" Thu 02:00-03:30pm, 2.058 (20.30)
Winter term 2015/2016
- Lecture "L²-invariants" Thu 03:45-05:15 pm, room 2.058 (20.30)
- Problem class "L²-invariants" Mon 02:00-03:30 pm, room 2.059 (20.30)
Teaching assistant: Sabine Braun; Starts 10/26/2015 - RG Seminar "Topology" Thu 05:30-07:00 pm, room 2.058 (20.30)
More information on the lecture "L²-invariants" is given in the course announcement.
Summer term 2015
- Exercise class: "Algebraic Topology" Fri 11:30-01:00 pm, room 2.059 (20.30)
- Seminar: "Projektive Geometrie" Thu 05:30-07:00 pm, room 3.060 (20.30)
- RG Seminar: "Topology" Thu 02:00-03:30 pm, room 2.058 (20.30)
Past teaching
Former teaching in Göttingen
- Oberseminar: Lattices in Semisimple Lie Groups (with Jean-François Planchat, winter 2011/2012).
| Title | Type | Student |
|---|---|---|
| The Lefschetz fixed point theorem: from simplicial to CW complexes | Masterarbeit | Gotami Heller |
| Homologies and elations in the projective and Euclidean plane | Bachelorarbeit | Cédric Dujardin |
| L2-Betti numbers and profinite completions of groups | Master thesis | Nico Stucki |
| Construction of Thom spectra for bordism with G-structure | Bachelor thesis | Amelie Flatt |
| Since April 2015 | Postdoc at Institute for Algebra and Geometry (working with Roman Sauer) |
Karlsruhe Institute of Technology |
| July 2013 - March 2015 | Postdoc at Mathematical Institute (working with Wolfgang Lück) |
University of Bonn |
| July 2010 - May 2013 | Doctoral studies at Mathematical Institute (working with Thomas Schick) |
University of Göttingen |
| August 2009 - June 2010 | Fulbright scholar at Department of Mathematics | University of California Berkeley |
| July 2008 - October 2008 | Internship in team "Quantitative Analysis" | Deutsche Postbank, Bonn |
| October 2004 - July 2009 | Diploma studies in mathematics with minor theoretical physics | University of Göttingen |
