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Invited presentations

• Certifying compact topological 4-manifolds? [after Freedman and Zuddas], Workshop on 4-manifolds and algorithms , Universität Regensburg, September 2024.
• The dynamical view on gradient invariants of groups, Joint Mathematics Colloquium (ICMAT-UAM-UC3M-UCIM) , UAM Madrid, May 2024.
  Pre-interview (in Spanish, translated from the English original)
• Dynamical upper bounds for homological gradient invariants, Homology Growth in Topology and Group Theory , MPIM Bonn, May 2024.
• Alle Gleichheiten sind gleich, aber manche sind gleicher. Von der Homotopietheorie zur Computerverifikation , From Analysis to Homotopy Theory. A conference in honor of Ulrich Bunke's 60th birthday , public evening lecture for a general audience , Alfried Krupp Wissenschaftskolleg, Greifswald, May 2024.
• A quadratic lower bound for the number of minimal geodesics , Geometry Seminar, Università di Pisa, March 2024.
• In dulci calculo ..., Weihnachtskolloquium, Mathematisches Institut, Universität Heidelberg, December 2023.
• Unattainable values, SwissKnots 2023, Universität Regensburg, September 2023.
• Vanishing of logarithmic torsion homology growth via dynamics, video, GAGTA 2023 at ESI, Wien, July 2023.
• Exponential growth rates in hyperbolic groups (after Koji Fujiwara and Zlil Sela) , Séminaire Bourbaki , Paris, April 2023.
• A new lower bound for the number of minimal geodesics, Bavarian Geometry and Topology Meeting XI, LMU München, January 2023.
• L^2-Betti numbers and computability of reals , Computability Theory and Applications Online Seminar , online, November 2022.
• Cup-products in bounded cohomology , Seminario a distancia de Teoría geométrica de grupos en México , online, Mexico, October 2022.
• Gradient invariants of aspherical manifolds with small amenable multiplicity , Conference: Arithmetic Groups and 3-Manifolds , (online talk) MPIM Bonn, May 2022.
• The spectrum of simplicial volume: groups, manifolds, and questions, Geometry Seminar, ETH Zürich, May 2022.
• Lower multiplicity bounds via classifying spaces , AATRN Topological Complexity Seminar , online, April 2022
• Computations in bounded cohomology , Topological and Homological Methods in Group Theory 2022 , Bielefeld, March 2022
• Covering spaces by "small" subsets, Pure Mathematics Colloquium (online talk), University of Southampton, February 2022
• Gradient invariants of aspherical manifolds with small amenable category, International young seminar on bounded cohomology and simplicial volume (ICMAT/ETHZ/UR; online), January 2022
• Computations in bounded cohomology, Kolloquium Mathematische Gesellschaft (online talk), Georg-August-Universität Göttingen, November 2021
• Simplicial volume: values and applications, Sektion Geometrie und Topologie (online talk), DMV-ÖMG-Tagung, September 2021
• Computing bounded cohomology?, HCM Symposium (online talk), Universität Bonn, August 2021.
• The spectrum of simplicial volume of non-compact manifolds, International young seminar on bounded cohomology and simplicial volume (ENS Lyon/ETHZ/UR; online), June 2021
• Stable integral simplicial volume of 3-manifolds, Topology seminar (online), University of California Santa Barbara, May 2021.
• Open covers with geometric pi_1-constraints, Topology seminar (online), University Notre Dame, May 2021.
• Amenable covers of manifolds, Operator Algebras Seminar (online), IMJ-PRG, Paris, April 2021.
• Rank gradient, cost, and simplicial volume, Geometric Group Theory Seminar (online), University of Cambridge, March 2021.
• The spectrum of simplicial volume I: foundations (II: scl by Nicolaus Heuer), Geometry Seminar (online), University of Chicago, March 2021.
• Simplicial volume of one-relator groups, RTG 2229 Colloquium (online), KIT, February 2021.
• Computing simplicial volumes, Killing Kolloquium (online), WWU Münster, January 2021
• Simplicial volume of one-relator groups, Algebra Seminar (online), Brasilia University, December 2020
• Amenable covers, Pure Maths Colloquium (online), October 2020, Sheffield
• Simplicial volume and stable commutator length (pre-talk on simplicial volume), Geometry and Analysis on Groups Research Seminar (online), Universität Wien, October 2020.
• Stable integral simplicial volume, International young seminar on bounded cohomology and simplicial volume (ENS Lyon/UR; online), July 2020
• p-Adic simplicial volumes, Geometry Seminar (online), May 2020, ETH Zürich
• Ergodic theoretic methods in group homology: A mini-course on L^2-Betti numbers in group theory, summer school Random and arithmetic structures in topology, June 2019 MSRI, Berkeley
• The spectrum of simplicial volume: From groups to manifolds, Felix-Klein-Kolloquium, May 2019, Düsseldorf
• A dynamical view on simplicial volume, Growth in Topology and Number Theory, July 2018, Bonn
• Simplicial volume of one-relator groups, Seminar Algebra-Geometrie-Kombinatorik, June 2018, TU Dresden
• Simplicial volume: Fillings, gaps, and one-relator groups, 29th NRW Topology Meeting, April 2018, Bonn
• Twisted simplicial volumes, Bavarian Geometry/Topology Meeting II , December 2017, Universität Augsburg
• The uniform boundary condition and simplicial volumes , video , Group actions and cohomology in non-positive curvature, June 2017, Isaac Newton Institute for Mathematical Sciences, Cambridge.
• Approximating simplicial volumes by their integral analogues, Groups, Manifolds & K-Theory, A conference on the occasion of Wolfgang Lück's 60th birthday, June 2017, WWU Münster.
• The uniform boundary condition without bounded cohomology, Geometry Seminar, January 2017, Universität Heidelberg.
• Gradient invariants of groups vs. simplicial volumes, Groups, Graphs, Action!, Fall Conference of the Swiss Mathematical Society, October 2015, University of Neuchâtel.
• Simplicial volumes of amenable manifolds, AG Seminar Topologie, July 2015, KIT Karlsruhe.
• Simplicial volumes of amenable manifolds, GK Colloquium, June 2015, Georg-August Universität Göttingen.
• Bounded-cohomological dimension of discrete groups , Séminaires Groupes et Géométrie, May 2015, Université de Genève.
• Manifolds with small integral simplicial volume , Geometry Seminar, May 2015, ETH Zürich.
• Bounded-cohomological dimension of discrete groups , 23rd NRW Topology Meeting April 2015, WWU Münster.
• The l^infty-semi-norm on uniformly finite homology , Seminari di Geometria, March 2015, Pisa.
• Integral approximations of simplicial volume , Oberseminar Topologie, November 2014, Bonn.
• Integral foliated simplicial volume of hyperbolic 3-manifolds , Groups and Topology (DMV-PTM Meeting Poznań/Satellite Conference Będlewo) September 2014, Poznań.
• Isomorphisms of Cayley graphs of finitely generated Abelian groups , Program: Geometric and Analytic Aspects of Group Theory, March 2012, Institut Mittag Leffler , Djursholm.
• Simply connected inflexible manifolds , Fakultätskolloquium, December 2011, TU München.
• Functorial semi-norms in homology and geometry , video , Chern Centennial Conference , November 2011, MSRI, Berkeley.
• Functorial semi-norms on singular homology , トポロジー火曜セミナー , September 2011, University of Tokyo.
• Functorial semi-norms in homology and mapping degrees, workshop "Arithmetic Groups vs. Mapping Class Groups: Similarities, Analogies and Differences" June 2011, Oberwolfach.
• Functorial semi-norms in homology and (in)flexible manifolds May 2011, Oberseminar Geometrie, LMU München.
• Functorial semi-norms in homology and (in)flexible manifolds April 2011, Oberseminar Topologie, Universität Bonn.
• Functorial semi-norms in homology and (in)flexible manifolds February 2011, Seminar Algebra and Geometry, Universität Leipzig.
• Manifolds not presentable by products February 2010, Mathematisches Kolloquium, Universität Regensburg.
• Manifolds and groups not presentable by products, November 2009, HIM Trimester Program on Rigidity : Workshop: Rigidity in cohomology, K-theory, geometry and ergodic theory , HIM Bonn.
• Fundamental classes not representable by products August 2009, Summer School Geometry and Rigidity of Groups , WWU Münster.
• Fundamental classes not representable by products February 2009, Topology Seminar, University of Aberdeen
• Simplicial volume of non-compact manifolds September 2008, Workshop Topologie, Oberwolfach
• (In)Varianten September 2008, Mathe-Tage WWU Münster.
• Simplicial volume of non-compact manifolds April 2008, Ninth NRW Topology Meeting , WWU Münster.
• Isomorphisms in l^1-homology October 2007, Oberseminar Topologie, Universität Bonn.
• Save early, save often! October 2007, (Post)Doktorandentreffen Rothenberge.
• Lipschitz simplicial volume (preprints with similar content: pdf, pdf ). April 2007, Geometry/Topology Seminar, University of Chicago.
• Isomorphisms in l^1-homology January 2007, Geometrie-Seminar, ETH Zürich, Switzerland.
• Isomorphisms in l^1-homology January 2007, Oberseminar Geometrie, LMU München.
• Simplicial volume and L^2-Betti numbers November 2006, Colloquium of the Graduiertenkolleg "Gruppen und Geometrie", Göttingen.
• Simplicial volume and L^2-Betti numbers April 2006, Differential Topology seminar at Kyoto University, Japan.

Notes of talks given at the Universität Regensburg

• Mathematik oder Numerogeopoesie?, Eine Stunde Mathematik-Didaktik, Universität Regensburg, May 2023.
• Der zentrale Grenzwertsatz, Kurzvortrag im Rahmen der Lehrkräftefortbildung zur Normalverteilung (09.03.2023; Didaktik der Mathematik, UR)
• Invarianten, Vorlesung im Rahmen des Schnupperstudiums Mathematik, September 2021.
• Slippery Slides GK-Ringvorlesung, January 2018.
• Unberechenbar? Erstsemestereinführung Karlstein, October 2017.
• Exercises in Academic Writing GK-Ringvorlesung, May 2017.
• Die Servietten-Vermutung (durchgeführt von Daniel Fauser und Johannes Prem) Erstsemestereinführung Karlstein, October 2016.
• Penrose-Parkettierungen (durchgeführt mit Daniel Fauser und Gesina Schwalbe), Workshop im Rahmen des Schnupperstudiums Mathematik, September 2016.
• Wie druckt man eine Mannigfaltigkeit? Über die Topologie des 3D-Drucks MNU-Landestagung der MNU Ostbayern , Februar 2016.
• Triangulierungen und Kartographie (zusammen mit Stefan Krauss), Workshop im Rahmen von MGR 2015, Oktober 2015.
• Eindeutigkeit von Slitherlink-Kurven (exercise sheet: pdf ), Eine Stunde Mathematik-Didaktik, Universität Regensburg, July 2015.
• The zeta-function in combinatorics (exercise sheet: pdf ), Ringvorlesung, GK CCC, June 2015.
• Triangulierungen und Kartographie (zusammen mit Stefan Krauss), Workshop im Rahmen von MGR 2014, Juli 2014.
• Slitherlink-Kurven -- ein Zusammenspiel von Kombinatorik, Topologie und Geometrie MNU-Landestagung der MNU Ostbayern , Februar 2014.
• Gruppen, Graphen, Symmetrie -- was sind negativ gekrümmte Gruppen? MNU-Landestagung der MNU Ostbayern , Februar 2012.
• Schülerinformationstag 2011 ( Mathematik-Workshop , Information zu den Studiengängen ), November 2011.
• Solitär: Es kann nur einen geben -- aber wo? Erstsemestereinführung Karlstein, October 2011.
• Invariance is bliss! -- Was ist algebraische Topologie? Antrittsvorlesung, July 2011

Outreach

• Alle Gleichheiten sind gleich, aber manche sind gleicher. Von der Homotopietheorie zur Computerverifikation , Conference From Analysis to Homotopy Theory. A conference in honor of Ulrich Bunke's 60th birthday , public evening lecture for a general audience , Alfried Krupp Wissenschaftskolleg, Greifswald, May 2024.
• 1, 2, 3, ... zu viele (Folien: pdf, Druckversion: pdf), Universität für Kinder, April 2019.
  Preprint-Version des Textes für den Vorlesungsband: pdf
• Mathematik für kleine Entdecker. Drei Experimente, Kindergarten St. Johannes, March 2018.
• Ecken und Kanten: Reguläre Polyeder bei Kepler Keplers Brennpunkte: Wissenschaft damals und heute (Fakultät für Physik, Keplerhaus der Stadt Regensburg, Fakultät für Mathematik), 50 Jahre UR, November 2017.
• Die Quinte und der Wolf -- über die Symmetrie der gleichstufigen Stimmung Goethe-Gymnasium Regensburg, Juli 2014.

Notes of seminar talks given at the WWU Münster

• Exotic aspherical manifolds SS 2009
• Margulis's normal subgroup theorem SS 2009
• Isomorphisms in l^1-homology WS 06/07
• The ergodic decomposition Theorem SS 2006
• Representation theory of Lie algebras SS 2006
• Nash equilibria SS 2005
• Homology and Seminorms SS 2005
• The Proportionality Principle of Simplicial Volume SS 2004
• Simplicial Volume WS 03/04
• Stationäre Maße und Zeitmittel SS 2003
• Mannigfaltigkeiten halten nicht WS 02/03
• Normal Forms for Letterless Fragments of GLP WS 02/03
• Packen weniger kongruenter Kreise in ein Quadrat WS 02/03
• Schnittzahlen von ebenen algebraischen Kurven , Der Satz von Bezout SS 2002
• Instructions for Obstructions ( lange Version - zusammen mit Marcus Meyer) Hindernisse für Schnitte von Faserungen ( Hindernisse und charakteristische Klassen - von Marcus Meyer) WS 01/02

Notes of seminar talks given at the University of Konstanz

• Fixpunktmengen gewisser Z/2-Operationen SS 2001
• Klassifikation der kompakten Flächen SS 2000