Prof. Dr. Roman Sauer
 Head of topology group
 Office Hours: nach Vereinbarung
 Room: 1.001
 Phone: +49 721 60846325
 Fax: +49 721 60842148
 roman sauer ∂kit edu
Karlsruher Institut für Technologie
MATH  IAG  AG Topologie
Englerstr. 2  Mathebau (20.30)
76131 Karlsruhe
Publications  Roman Sauer
Preprints
 Bounded cohomology of amenable covers via classifying spaces
joint with Clara Löh
to appear in L’Enseignement Mathématique
[arXiv:1910.11716]
 Profinite invariants of arithmetic groups
joint with Holger Kammeyer, Steffen Kionke and Jean Raimbault
to appear in Forum of Mathematics, Sigma
[arXiv:1901.01227]
 Sarithmetic spinor groups with the same finite quotients and distinct l²cohomology
joint with Holger Kammeyer
to appear in Groups, Geometry, and Dynamics
[arXiv:1804.10604]
 Homology and homotopy complexity in negative curvature
joint with Uri Bader and Tsachik Gelander
to appear in Journal of the European Mathematical Society
[arXiv:1612.04871]
[TOP]
Research articles
 Lattice Envelopes
joint with Uri Bader and Alex Furman
Duke Mathematical Journal (2020).
[Journal] [arXiv:1711.08410]
 Counting maximally broken Morse trajectories on aspherical manifolds
joint with Caterina Campagnolo
Geometriae Dedicata 202 (2019), 387–399.
[Journal] [arXiv:1808.08737] [MR4001823]
 An adelic arithmeticity theorem for lattices in products
joint with Uri Bader and Alex Furman
Math. Z. 293 (2019), no. 34, 1181–1199.
[Journal] [arXiv:1705.08158] [MR4024582]
 Vanishing of l²Betti numbers of locally compact groups as an invariant of coarse equivalence
joint with Michael Schrödl
Fund. Math. 243 (2018), no. 3, 301–311.
[arXiv:1702.01685] [Journal] [MR3863061]
 l²Betti numbers of totally disconnected groups and their approximation by Betti numbers of lattices
joint with Henrik D. Petersen and Andreas Thom
J. Topol. 11 (2018), no. 1, 257–282.
[arXiv:1612.04559] [Journal] [MR3784232]
 Cantor systems and quasiisometry of groups
joint with Kostya Medynets and Andreas Thom
Bulletin of the LMS 49 (2017), no. 4, 709–724
[arXiv:1508.07578] [Journal] [MR3725491]
 Topological models of finite type for tree almost automorphism groups
joint with Werner Thumann
Int. Math. Res. Not. IMRN 2017, no. 23, 7292–7320.
[arXiv: 1510.05554] [Journal] [MR3801421]
 Integral foliated simplicial volume of aspherical manifolds
joint with Roberto Frigerio and Clara Löh and Cristina Pagliantini
Israel J. Math. 216 (2016), no. 2, 707–751
[arXiv:1506.05567] [Journal] [MR3557463]
 Volume and homology growth of aspherical manifolds
Geom. Topol. 20 (2016), 10351059
[arXiv: 1403.7319] [Journal] [MR3493098]
 On the structure and arithmeticity of lattice envelopes
joint with Uri Bader and Alex Furman
C. R. Math. Acad. Sci. Paris 353 (2015), no. 5, 409–413.
[arXiv:1411.7332] [Journal] [MR3334993]
 L²invisibility and a class of local similarity groups
joint with Werner Thumann
Compositio Math.150 (2014), no. 10, 17421754
[arXiv:1304.6843] [Journal] [MR3269466]
 On the growth of Betti numbers in padic analytic towers
joint with Nicolas Bergeron and Peter Linnell and Wolfgang Lück
Groups Geom. Dyn. 8 (2014), no. 2, 311–329
[arXiv:1204.3298] [Journal] [MR3231217]
 Weak notions of normality and vanishing up to rank in L²cohomology
joint with Uri Bader and Alex Furman
Int. Math. Res. Not. IMRN 2014, no. 12, 3177–3189
[arXiv:1206.4793] [Journal] [MR3217658]
 On the cohomology of weakly almost periodic group representations
joint with Uri Bader and Christian Rosendal
Journal of Topology and Analysis 6 (2014), no. 2, 153165
[arXiv:1302.1392] [Journal] [MR3191647]
 Integrable measure equivalence and rigidity of hyperbolic lattices
joint with Uri Bader and Alex Furman
Inventiones Math. 194 (2013), No. 2, 313–379
[arXiv:1006.5193] [Journal] [MR3117525]
 Efficient subdivision in hyperbolic groups and applications
joint with Uri Bader and Alex Furman
Groups, Geometry, and Dynamics 7 (2013), 263292
[arXiv:1003.1562] [Journal] [MR3054570]
 Euler characteristics of categories and homotopy colimits
joint with Tom Fiore and Wolfgang Lück
Documenta Math. 16 (2011), 301354
[arXiv:1007.3868] [Journal] [MR2804514]
 Spectral distribution and L²isoperimetric profile of Laplace operators on groups
joint with Alexander Bendikov and Christophe Pittet
Mathematische Annalen 354 (2012), 4372
[arXiv:0901.0271] [Journal] [MR2957618]
 Finiteness obstructions and Euler characteristics of categories
joint with Tom Fiore and Wolfgang Lück
Advances in Mathematics 226 (2011), no. 3, 2371–2469
[arXiv:0908.3417] [Journal] [MR2739781]
 The limit of F_pBetti numbers of a tower of finite covers with amenable fundamental groups
joint with Peter Linnell and Wolfgang Lück
Proc. Amer. Math. Soc. 139 (2011), 421434
[arXiv:1003.0434] [Journal] [MR2736326]
 L²torsion, the measuretheoretic determinant conjecture, and uniform measure equivalence
joint with Wolfgang Lück and Christian Wegner
Journal of Topology and Analysis 2 (2010), no. 2, 145171
[arXiv:0903.2925] [Journal] [MR2652905]
 A spectral sequence to compute L²Betti numbers of groups and groupoids
joint with Andreas Thom
Journal of the London Mathematical Society 81 (2010), no. 3, 747773
[arXiv:0707.0906] [Journal] [MR2650795]
 Degree theorems and Lipschitz simplicial volume for nonpositively curved manifolds of finite volume
joint with Clara Löh
Journal of Topology 2 (2009), no. 1, 193225
[arXiv:0710.1635] [Journal] [MR2499443]
 Simplicial Volume of Hilbert modular varieties
joint with Clara Löh
Commentarii Mathematici Helvetici 84 (2009), no. 3, 457470
[arXiv:0706.3904] [Journal] [MR2507250]
 Amenable covers, volume and L²Betti numbers of aspherical manifolds
J. Reine Angew. Math (Crelle's Journal) 636 (2009), 4792
[math.AT/0605627] [Journal] [MR2572246]
 Homological invariants and quasiisometry
Geom. Funct. Anal. (GAFA) 16 (2006), no. 2, 476–515
[math.AT/0312129] [Journal] [MR2231471]
 L²Betti numbers of discrete measured groupoids
Internat. J. Algebra Comput. 15 (2005), no. 56, 1169–1188
[math.AT/0312411] [Journal] [MR2197826]
 Power series over the group ring of a free group and applications to NovikovShubin invariants
Proceedings of the School HighDimensional Manifold Topology, Trieste, 2003.
[pdf] [MR2048733]
[TOP]
Expository articles
 l²Betti numbers of discrete and nondiscrete groups
in: London Mathematical Society Lecture Note Series 447, Cambridge University Press 2018
[arXiv:1509.05234] [Journal] [MR3793289]
 Homotopy invariance of almost flat Betti numbers
joint with Thomas Schick
Enseign. Math. (2) 54 (2008), no. 12 (Guido's book of conjectures)
[pdf] [MR2454697]
 Volume and L²Betti numbers of aspherical manifolds
Proceedings of the Courant Colloquium Göttingen 2007 (ISBN 39783940344564)
[Online edition] [pdf] [MR2906042]
[TOP]
Miscellaneous
 The asymptotic growth of twisted torsion
joint with Nicolas Bergeron and Wolfgang Lück
[pdf]
[TOP]
Conferences  Roman Sauer

Workshop: Geometry, Topology and Computation
Workshop
June 12th  14th, 2019
Universität Heidelberg
Weitere Organisatoren: Peter Albers, Anna Wienhard

Workshop: Riemannian and Simplicial Volume
Workshop
April 8th  11th, 2019
Karlsruher Institut für Technologie
Weitere Organisatoren: Caterina Campagnolo, Clara Löh

HeidelbergKarlsruheStrasbourg Geometry Day XII
Workshop
November 30th, 2018
Universität Heidelberg
Weitere Organisatoren: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day XI
Workshop
June 22nd, 2018
Karlsruher Institut für Technologie
Weitere Organisatoren: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day VIII
Workshop
December 1st, 2017
University Heidelberg
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

Growth in Geometry and Topology
Summer School
August 21st  25th, 2017
Les Diablerets
Other organizers: Vincent Emery, Ruth Kellerhals, Stefan Wenger

Asymptotic geometry of groups and spaces
Conference
February 20th  23rd, 2017
University Heidelberg
Other organizers: Daniele Alessandrini, Beatrice Pozzetti, Petra Schwer, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day VII
Workshop
April 22nd, 2016
University Strasbourg
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day VI
Workshop
Oktober 30th, 2015
University Heidelberg
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

Topology Retreat
Retreat
September 29th  October 3rd, 2015
Będlewo, Poland
Other organizers: Piotr Nowak

HeidelbergKarlsruheStrasbourg Geometry Day V
Workshop
June 6th, 2014
Karlsruhe Institute of Technology
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day IV
Workshop
January 24th, 2014
University Heidelberg
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day III
Workshop
October 18th, 2013
Université de Strasbourg
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

GGTConference 2013
Conference
October 7th  11th, 2013
Karlsruhe Institute of Technology
[poster]
Other organizers: Wilderich Tuschmann, Gabriela WeitzeSchmithüsen

HeidelbergKarlsruheStrasbourg Geometry Day II
Workshop
May 24th, 2013
Karlsruhe Institute of Technology
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

HeidelbergKarlsruheStrasbourg Geometry Day I
Workshop
Januar 18th, 2013
University of Heidelberg
Other organizers: Olivier Guichard, Enrico Leuzinger, Anna Wienhard

"Actionnow"  Group Actions, their Dynamics and Geometry
Workshop
October 11th  12th, 2012
University of Berlin
[poster]
Other organizers: Tsachik Gelander, Holger Reich

Research Seminar on geometric group theory
Research Seminar
September 24th  27th, 2012
University of Münster
Other organizers: Petra Schwer

Flows on homogeneous spaces
Minerva Summer School
September 2nd  7th, 2012
Technion in Haifa/Israel
Other organizers: Uri Bader, Francoise Dal'Bo

New Horizons for Simplicial Volume and The Barycenter Method
AIM Square Program
August 6th  10th, 2012
American Institute of Mathematics, Palo Alto
Other organizers: Michelle Bucher, Chris Connell, Jean Lafont, Ben Schmidt

Geometry and Rigidity of Groups
Summer School
August 24th  28th, 2009
University of Münster
Other organizers: Arthur Bartels, Wolfgang Lück

Analysis on metric spaces
Research Seminar
Winter 2008
University of Chicago
Other organizers: Shmuel Weinberger

L²Invariants, Measure Theory and Geometric Group Theory
Workshop
March 8th  12th, 2004
University of Münster
[Booklet]
Other organizers: Damien Gaboriau, Wolfgang Lück, Andrzej Zuk
Talks  Roman Sauer
2019
 TU Dresden, Conference: Geometry and Approximation, August 2019
 University Heidelberg, Workshop on Bounded Cohomology, July 2019
 Cortona, Conference and summer school: Geometry of scalar curvature, July 2019
 IMPAN Warsaw, Simons Semester: Geometric and Analytic Group Theory, June 2019
 Universita di Pisa, Seminari di Geometria, March 2019
2018
 University Regensburg, Colloquium, December 2018
 University Regensburg, Seminar, December 2018
 University Geneva, SMSDMV workshop: Spectra and l^{2}invariants, September 2018
 Hausdorff Center for Mathematics Bonn, Conference: Growth in Topology and Number Theory, July 2018
 ICMAT Madrid, Workshop in the thematic program: l^{2}Betti numbers and their analogues in positive characteristic, June 2018
 Cuny Graduate Center New York, February 2018
 Bernoulli Center Lausanne, Conference: Borel combinatorics and ergodic theory, February 2018
2017
 Universität Gießen, Seminar LieTheorie, Geometrie und Differentialgleichungen, February 2017
 Universita di Pisa, Seminari di Geometria, April 2017
 TU Dresden, Colloquium, May 2017
 Newton Institute Cambridge, Conference: Group Actions and Cohomology in Nonpositive Curvature, June 2017
 MFO Oberwolfach, Workshop on Geometric Structures in Group Theory, June 2017
 Les Diablerets, PhD School on Growth in Geometry and Topology, August 2017
2016
 WWU Münster, Topology Seminar, January 2016
 Augsburg University, Colloquium, February 2016
 ESI Conference Wien: Measured Group Theory, February 2016
 Bielefeld University, Conference: Topological and Homological Methods in Group Theory, April 2016
 Université de Fribourg, Colloquium, April 2016
 LMU München, October 2016
2015
 Universität Dresden, Conference: Groups and Topological Groups, July 2015
 Universita di Pisa, Geometry seminar, May 2015
 Vanderbilt University, Nashville, Thirteenth Annual NCGOA Spring Institute, May 2015
 University of Texas, Austin, Groups and Dynamics Workshop, March 2015
 Sde Boker, Workshop on Generalized Cohomology, February 2015
2014
 Universität Wien, Seminar: Geometry and Analysis on Groups, December 2014
 Universität Bonn, 22. NRWTopology Meeting, November 2014
 MFO Oberwolfach, Arbeitstagung: Totally Disconnected Groups, October 2014
 Bedlewo/Poznan, Polen, Conference: Groups and Topology, September 2014
 Technion, Haifa, Colloquium, May 2014
 Hebrew University, Jerusalem, Colloquium, March 2014
 BarIlan, Tel Aviv, Colloquium, March 2014
 Technion, Haifa, Actionnow Seminar, March 2014
 MPI Bonn, Homology Growth Seminar, February 2014
2013
 University of Copenhagen, Workshop: Classifying Spaces, Loop Spaces and Finiteness, October 2013
 Ventotene, Italy , Conference: Geometric and Analytic Group Theory, September 2013
 MFO Oberwolfach, Workshop: Group Theory, Measure, and Asymptotic Invariants, August 2013
 University of Leipzig, Colloquium, June 2013
 Université de Fribourg, Colloquium, April 2013
 University of Bonn, Seminar Topology, April 2013
2012
 University of Berlin, Topology and Groups, June 2012
 LMU München, Geometry Seminar, May 2012
 MittagLeffler Institute, Stockholm, Geometric and Analytic Aspects of Group Theory, April 2012
2011
 Beit Hatfutsot, Tel Aviv, Transcending Tradition  Jewish Mathematicians in GermanSpeaking Academic Culture, November 2011
 Technion, Haifa, Conference on Geometric Group Theory, June 2011
 University of Bonn, 14th NRW Topology Meeting, November 2011
2010
 MFO Oberwolfach, Workshop: Actions and Invariants of Residually Finite Groups: Asymptotic Methods, September 2010
 Technion, Haifa, Geometry Seminar, June 2010
 ETH Zürich, Algebra and Topology Seminar, March 2010
 ETH Zürich, Geometry Seminar, March 2010
 University of Copenhagen, Workshop: Von Neumann Algebras and Group Actions, February 2010
2009
 University of Regensburg, Colloquium, December 2009
[Slides]
 University of Osnabrück, Colloquium, October 2009
 University of Göttingen, Lecture series on "Measurable Group Theory as a Tool in Geometry", August 2009
[Notes by Anke Pohl]
 WWU Münster, Habilitationskolloquium, July 2009
 University of Illinois at Chicago, Geometry, Topology, and Dynamics Seminar, March 2009
 University of Regensburg, Colloquium, March 2009
2008
 University of Regensburg, Colloquium of the KeplerForschungszentrums, November 2008
 LMU München, DifferentialtopologySeminar, November 2008
 MFO Oberwolfach, Workshop on von Neumann Algebras and Ergodic Theory of Group Actions, November 2008
 University of Stuttgart, Colloquium, October 2008
[Slides]
 MFO Oberwolfach, Topology Workshop, September 2008
 Banff International Research Station, Topics in von Neumann Algebras, March 2008
[Slides] [Handout]
 University of Michigan, Geometry Seminar, February 12, 2008
2007
 Courant Research Center Göttingen, CourantColloquium "Göttingen trends in Mathematics", October 2007
[Slides] [Extended notes]
 WWU Münster, Topology Seminar, October 2007
 Banff International Research Station, Topological and Geometric Rigidity, July 2007
[Slides]
 Binghamton University, Topology Seminar, April 2007
 University of Illinois at UrbanaChampaign, Seminar, April 2007
 Banff International Research Station, Topology, February 2007
 Ohio State University, Seminar, February 2007
2006
 University of Illinois at Chicago, Geometry, Topology, and Dynamics Seminar, November 2006
 University of Karlsruhe, Conference on "Geometry and algebra of solvable groups", October 2006
 MPI Bonn, Activity on Geometry and Group Theory, July 2006
 MPI Bonn, Topology Seminar, July 2006
 CRM Montreal, Conference on Geometric Group Theory, July 2006
 MFO Oberwolfach, Topological and Geometric Methods in Group Theory, April 2006
 University of South Alabama, G3conference, March 2006
 University of Chicago, Topology/Geometry Seminar, March 2006
 LMU München, DifferentialtopologySeminar, January 2006
2005
 Vanderbilt University of Nashville, Third Annual Spring Institute on Noncommutative Geometry and Operator Algebras, May 2005
 University of Tel Aviv, Seminar, May 2005
 Hebrew University Jerusalem, Seminar, May 2005
 University of Göttingen, GKColloquium, January 2005
2004
 Luminy, Seminar, November 2004
 University of Marseille, Seminar, November 2004
 ENS Lyon, ENSSeminar, November 2004
 University of Grenoble, Tripod Seminaire, November 2004
 MFO Oberwolfach, Topology Workshop, September 2004
 Bonn, 14. NRW Topology Meeting, April 2004
 Diablerets, Invariants sous QuasiIsometrie, April 2004
2003
 University of Augsburg, DifferentialgeometrySeminar, November 2003
 ETH Zürich, Seminar, June 2003
2001
 University of Basel, Seminar, November 2001