Jun.Prof. Dr. Holger Kammeyer Mathematical Institute Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf, Germany building: 25.22, office: 03.48 phone: +49 211 81 14490 email: holger.kammeyer@hhu.de 
I am assistant professor for "algebra and geometry" at the Mathematical Institute of Heinrich Heine University Düsseldorf in the algebra and number theory group. My research interests range around algebraic topology, ℓ²invariants, profinite and arithmetic groups. I am PI within the Priority Program 2026 "Geometry at Infinity" and member of the RTG 2240 "AlgebroGeometric Methods in Algebra, Arithmetic and Topology".
Arithmetic Groups and 3Manifolds A hybrid conference at the Max Planck Institute for Mathematics in Bonn, Germany, May 16th  20th, 2022. Jointly organized with Steffen Kionke, Haluk Sengun, and Alan Reid. Sign up now! 

Title  Coauthors  Year 
On absolutely profinitely solitary lattices in higher rank Lie groups  2022  
On the profinite rigidity of lattices in higher rank Lie groups  S. Kionke  2020 
Title  Coauthors  Journal 
Introduction to Algebraic Topology  to appear in Birkhäuser Compact Textbooks in Mathematics  
Adelic superrigidity and profinitely solitary lattices  S. Kionke  Pacific Journal of Mathematics 3131 (2021), 137158 
Products of free groups in Lie groups  C. Campagnolo  Journal of Algebra, Volume 579, (2021), 237255 
Profinite commensurability of Sarithmetic groups  Acta Arithmetica, 197.3 (2021), 311330  
Profinite invariants of arithmetic groups  S. Kionke, J. Raimbault, R. Sauer  Forum of Mathematics, Sigma, Vol. 8, (2020), 122 
Sarithmetic spinor groups with the same finite quotients and distinct ℓ²cohomology  R. Sauer  Groups, Geometry, and Dynamics, 14 (2020), no. 3, 857869 
From Betti numbers to ℓ²Betti numbers  R. Sauer  Snapshots of modern mathematics from Oberwolfach, (2020.01), 111 
Introduction to ℓ²invariants  Springer Lecture Notes in Mathematics, Vol. 2247 (2019), viii+181 pp  
The shrinkage type of knots  Bull. Lond. Math. Soc., 493 (2017), 428442  
Approximating NovikovShubin numbers of virtually cyclic coverings  Groups, Geometry, and Dynamics, 114 (2017), 12311251  
The FarrellJones conjecture for arbitrary lattices in virtually connected Lie groups  W. Lück, H. Rüping  Geometry & Topology, 203 (2016), 12751287 
ℓ²invariants of nonuniform lattices in semisimple Lie groups  Algebraic & Geometric Topology, 14 (2014), 24752509  
An explicit rational structure for real semisimple Lie algebras  Journal of Lie Theory, 24, No. 2 (2014), 307319  
The HestonHullWhite Model III: Design and Implementation  J. Kienitz  Wilmott Magazine, Issues 59, (May 2012), 4449 
The HestonHullWhite Model II: Numerics and Examples  J. Kienitz  Wilmott Magazine, Issues 58, (March 2012), 3445 
The HestonHullWhite Model I: Finance and Analytics  J. Kienitz  Wilmott Magazine, Issues 57, (Jan 2012), 4653 
Title  Type  University 
ℓ²invariants of nonuniform lattices in semisimple Lie groups  doctoral thesis  University of Göttingen 
On exotic manifolds  diploma thesis  University of Göttingen 
Title  Venue  Coorganized with 
Conference: Arithmetic Groups and 3manifolds  MPIM Bonn  S. Kionke, A. Reid, H. Sengun 
Conference: Arithmetic Groups and 3manifolds  University of Hagen  S. Kionke, H. Sengun 
Workshop: Current developments around the Atiyah conjecture  Karlsruhe Institute of Technology  B. Waßermann 
Workshop: New directions in ℓ²invariants  HIM Bonn  A. Kar, S. Kionke, J. Raimbault 
Lecture notes  Year 
Einführung in die Topologie (Introduction to topology)  2022 
Title  Type  Student 
The Lefschetz fixed point theorem: from simplicial to CW complexes  Master thesis  Gotami Heller 
Homologies and elations in the projective and Euclidean plane  Bachelor thesis  Cédric Dujardin 
ℓ²Betti numbers and profinite completions of groups  Master thesis  Nico Stucki 
Construction of Thom spectra for bordism with Gstructure  Bachelor thesis  Amelie Flatt 
Since August 2021  "Juniorprofessor" (assistant professor) for "algebra and geometry" at Mathematical Institute  Heinrich Heine University Düsseldorf 
November 2017  July 2021  "Akademischer Rat auf Zeit" (lecturer) at Institute for Algebra and Geometry 
Karlsruhe Institute of Technology 
April 2015  October 2017  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 
October 2004  July 2009  Diploma studies in mathematics with minor theoretical physics  University of Göttingen 