Universitat Wien

Geometric and Analytic Group Theory Research Group

Fakultät für Mathematik

"Geometry and Analysis on Groups" Research Seminar

Tuesdays, 15:15–17:15, Seminarraum 9, Oskar-Morgenstern-Platz 1, 2.Stock
Goulnara Arzhantseva and Chris Cashen

Research seminar overview

The first hour (15:15–16:00) of every seminar is an introductory lecture explaining basic notions that are going to appear during the second hour (16:15–17:00)—the regular research seminar presenting recent developments within Geometric and Analytic Group Theory and related fields.
The speaker typically joins the group for coffee and informal discussion prior to the seminar from 13:30–15:00 in either the 10.stock Besprechungsraum or the 12.stock Sky Lounge.

Wintersemester 2017/18

Oct 10Karen Vogtmann (University of Warwick), "Jewels in Outer space."Abstract
Oct 17Matthew Cordes (Technion), TBA.
Oct 24
Nov 7 Dawid Kielak (Universität Bielefeld), TBA.
Nov 14
Nov 21
Nov 28
Dec 5
Dec 12Alexander Bors (Universität Salzburg/Western Australia), "Fibers of word maps and composition factors."Abstract
Jan 9
Jan 16
Jan 23
Jan 30

Sommersemester 2017 Organized by Arzhantseva, Cashen, and Martin Finn-Sell.

Exceptionally, this semester was a mixture of research talks (R) and an introductory lecture course (L).
Jun 27Wolfgang Alexander Moens (Universität Wien), "The restricted Burnside problem and the refined Frobenius conjecture." (L)Abstract
Jun 13Martin Finn-Sell (Universität Wien), "Growth in groups and Gromov's theorem."(L)
May 30Martin Finn-Sell (Universität Wien), "Amenable groups and paradoxical representations."(L)
May 23Federico Berlai (Universidad del País Vasco/Euskal Herriko Unibertsitatea), "A refined combination theorem for hierarchically hyperbolic groups."(R)Abstract
May 16Alejandra Garrido (Heinrich Heine Universität Düsseldorf)- "Maximal subgroups of groups of intermediate growth."(R) Abstract
May 9Alexandre Martin (Universität Wien), "CAT(0) cube complexes and a survey of the virtual Haken conjecture."(L) Abstract
May 2Alexandre Martin (Universität Wien), "The basics of groups acting on trees."(L) Abstract
Apr 25Christopher Cashen (Universität Wien), "The Floyd boundary of a hyperbolic group is its Gromov boundary."(L) Abstract
Apr 4 Cesar Ceballos (Universität Wien), "The configuration space of a robotic arm in a tunnel." (R)Abstract
Mar 28 Martin Finn-Sell (Universität Wien), "An introduction to geometric and analytic group theory II."(L)
Mar 21 Martin Finn-Sell (Universität Wien), "An introduction to geometric and analytic group theory."(L)
Mar 9 Vadim Alekseev (TU-Dresden), "Invariant random positive definite functions and disintegration rigidity. "(R) Abstract
Mar 7 Michael Wibmer (University of Pennsylvania), "Difference algebraic groups." (R)Abstract

Wintersemester 2016/17

Jan 25 Ján Špakula (University of Southampton), "Coarse medians and Property A." Abstract
Jan 17 Mikael de la Salle (ENS de Lyon), "Characterizing a vertex-transitive graph by a large ball." Abstract
Dec 14 Alexandre Martin (Universität Wien), "On the small cancellation geometry of certain graph products of groups." Abstract
Dec 13 Nir Lazarovich (ETH Zürich), "Detecting sphere boundaries of hyperbolic groups." Abstract
Nov 23 Tullio Ceccherini-Silberstein (Università del Sannio), "Expansive actions of countable amenable groups, homoclinic pairs, and the Myhill property." Abstract
Nov 22 Federico Berlai (Universität Wien), "New residually amenable groups, permanence properties, and metric approximations." Abstract
Nov 22 Gabor Elek (Lancaster University), "Convergence and limits of representations of finite dimensional algebras."
Nov 15 Martin Finn-Sell (Universität Wien), "Amenability for étale groupoids, failures of Hulanicki's theorem and the weak containment story." Abstract
Nov 8 Peter Haïssinsky (Université d'Aix-Marseille), "Quasi-isometric rigidity of fundamental groups of compact 3–manifolds." Abstract
Oct 25 Nicolás Matte Bon (ETH Zürich), "Subgroup dynamics, extreme boundaries, and \(C^*\)–simplicity." Abstract
Oct 18 Christopher Cashen (Universität Wien), "The contracting boundary of a group." Abstract
Oct 11 Adrien Boyer (Weizmann Institute), "Monotony for boundary representations of free group." Abstract

Sommersemester 2016

July 5 Wolfgang Globke (University of Adelaide), "Étale modules for reductive algebraic groups."
Jun 29 Piotr Nowak (IMPAN/Uniwersytet Warszawski), "Spectral gaps, warped cones and the coarse Baum-Connes conjecture." Abstract
Jun 28 Markus Steenbock (Universität Wien), "Kaplansky's zero divisor conjecture, CAT(0) cubulation, and the unique product property." Abstract
Jun 28 Indira Chatterji (Université de Nice), "The median class for CAT(0) cubical complexes." Abstract
Jun 21 Andrei Minchenko (Universität Wien), "Differential Algebraic Groups and Their Applications." Abstract
Jun 15 Mark Sapir (Vanderbilt University), "On subgroups of R. Thompson group \(F\)." Abstract
Jun 14 Rémi Coulon (Université de Rennes), "Torsion groups acting properly on a CAT(0) cube complex." Abstract
Jun 08 Damian Osajda (Uniwersytet Wrocławski), "Burnside groups without property (T)."
Jun 08 Damian Osajda (Uniwersytet Wrocławski), "Classifying spaces for families of subgroups for systolic groups." Abstract
Jun 07 Elisabeth Fink (University of Ottawa), "Morse geodesics in lacunary hyperbolic groups." Abstract
May 10 John Mackay (University of Bristol), "Fixed point properties for groups acting on \(L^p\) spaces." Abstract
Apr 26 Martin Finn-Sell (Universität Wien), "Analytic properties of sofic groups."
Apr 19 Wolfgang Moens (Universität Wien), "Arithmetically-free group-gradings of algebras with the permutation-contraction property." Abstract
Apr 12 Alexandre Martin (Universität Wien), "Über-contractions and acylindrical hyperbolicity." Abstract
Apr 05 Martin Finn-Sell (Universität Wien), "How not to prove Thompson-like groups are exact (and three other short stories)." Abstract
Mar 15 François Dahmani (Université Joseph Fourier, Grenoble I), "A spectral theorem for random walks in Mapping Class Groups: the convergence of the stretching factors." Abstract
Mar 08 Henry Bradford (University of Cambridge), "Uniform Diameter Bounds in Pro-p Groups." Abstract

Wintersemester 2015/16

Jan 26 Maxime Gheysens (École Polytechnique Fédérale de Lausanne), "Amenability as an affine fixed-point property in Hilbert spaces." Abstract
Jan 19 Mark Hagen (University of Cambridge), "Geometry of hierarchically hyperbolic spaces." Abstract
Jan 12 Panos Papazoglou (University of Oxford), "Cutpoints of CAT(0) groups." Abstract
Dec 15 Anthony Genevois (Aix-Marseille Université), "Acylindrical hyperbolicity of diagram groups from cubical geometry." Abstract
Dec 01 Thibault Pillon (Université de Genève), "Fibred property A." Abstract
Nov 24 Johannes Cuno (Technische Universität Graz), "The Tits alternative for non-spherical triangles of groups." Abstract
Nov 17 Uli Wagner (Institute of Science and Technology Austria), "Higher-dimensional expansion and topological overlap." Abstract
Nov 10 Markus Steenbock (Universität Wien), "Strong Atiyah conjecture for free groups and small cancellation groups". Abstract
Nov 03 Karl Auinger (Universität Wien), "Profinite graphs and the Ribes–Zalesskiĭ-Theorem." Abstract
Oct 27 Christopher Cashen (Universität Wien), "Contracting geodesics in graphical small cancellation groups." Abstract
Oct 20 Tracy Payne (Idaho State University), "Anosov maps on nilmanifolds." Abstract
Oct 13 JiaWen Zhang, (Universität Wien), "(Straight) Finite Decomposition Complexity for automata groups and box spaces." Abstract

Sommersemester 2015

Jun 17 Martin Finn-Sell (Universität Wien), "Some new negative results about box spaces."
Jun 16 Yash Lodha (EPFL), "A nonamenable finitely presented group of piecewise projective homeomorphisms." Abstract
Jun 09 Martin Finn-Sell (Universität Wien), "Some new positive results about box spaces."
Jun 02 Mark Sapir (Vanderbilt University), "Diagram groups and knots." Abstract
May 19 Karl Lorensen (Pennsylvania State University, Altoona), "Cohomology of solvable groups of finite rank." Abstract
May 12 Liviu Paunescu (IMAR, Bucharest), "On the Birkhoff - von Neumann theorem in type \(\mathrm{II}_1\) setting." Abstract
May 06 Martino Lupini (Universität Wien), "Fraisse theory and universal objects in group theory and metric geometry." Abstract
May 05 Martino Lupini (Universität Wien), "Borel complexity theory and Gromov's program." Abstract
Apr 28 Nick Wright (University of Southampton), "Geometric Examples of the Baum-Connes conjecture and Langlands duality." Abstract
Apr 21 Arnaud Hilion (Aix-Marseille Université), "Trees, currents and systems of partial isometries." Abstract
Apr 14 Anne Thomas (University of Glasgow), "Quasi-isometry classification of certain hyperbolic right-angled Coxeter groups." Abstract
Mar 24 Klaus Schmidt (Universität Wien), "Ergodicity of algebraic group actions." Abstract
Mar 17 David Hume (Université Catholique de Louvain), "Separation and Expanders." Abstract
Mar 11 Rudolf Zeidler (Universität Göttingen), "Large scale index theory and positive scalar curvature." Abstract

Wintersemester 2014/15

Jan 27 Camille Horbez (Université Rennes 1), "The Tits alternative for the automorphism group of a free product." Abstract
Jan 20 Dominik Gruber (Universität Wien), "On infinitely presented graphical small cancellation groups." Abstract
Dec 16 Christopher Cashen (Universität Wien), "Fibrations of Mapping Tori of Polynomially Growing Free Group Automorphisms." Abstract
Dec 09 Roman Sauer (Karlsruhe Inst. Tech.-IAG), "Lattices envelopes." Abstract
Dec 02 Markus Steenbock (Universität Wien), "A combination theorem for cubulation in small cancellation theory over free products."Abstract
Nov 25 Michal Ferov (University of Southampton), "Conjugacy separability in graph products of groups." Abstract
Nov 18 Adrien Le Boudec (Université Paris-Sud 11), "Locally compact lacunary hyperbolic groups." Abstract
Nov 11 Jean Raimbault (Université Paul Sabatier, Toulouse III), "On a property of geometric actions of groups." Abstract
Nov 05 Harald Helfgott (CNRS - Paris VI/VII), "The ternary Goldbach conjecture." (Kolloquiumsvortrag) Abstract
Nov 04 Liviu Paunescu (IMAR, Bucharest), "Almost commuting permutations are near commuting permutations." Abstract
Oct 28 Federico Berlai (Universität Wien), "Stably finite groups". Abstract
Oct 21 Martin Finn-Sell (Universität Wien), "Some analytic consequences of coarsely containing an expander." Abstract
Oct 14 Neha Gupta (University of Illinois), "Nielsen Equivalence Classes in a Class of Random Groups." Abstract

2010-2014 Organized by Goulnara Arzhantseva and Damian Osajda.

Sommersemester 2014

17.06 Dominika Pawlik (Uniwersytet Warszawski), "Automaticity of hyperbolic groups and analogous properties of their Gromov boundaries." Abstract
28.05 Ján Špakula (University of Southampton), "Green metric and boundaries of hyperbolic groups." Abstract
27.05 Natasa Macura (Trinity University), "CAT(0) spaces with polynomial divergence of geodesics." Abstract
20.05 Liviu Paunescu (IMAR), "Sofic representations that cannot be extended." Abstract
13.05 Piotr Nowak (Polska Akademia Nauk and Uniwersytet Warszawski), "Rigidity for actions on Banach spaces and Poincare inequalities." Abstract
7.05 Florin Radulescu (University of Rome 2, IMAR), "Hecke operators, discrete series unitary representations and Operator Algebras." Abstract
6.05 Martin Finn-Sell (Universität Göttingen), "Boundary a-T-menability for large girth expander graphs." Abstract
9.04 Andrew Duncan (Newcastle University), "Subgroups of the automorphism groups of partially commutative groups (RAAGs)." Abstract
9.04 Christopher Cashen (Universität Wien), "Quasi-isometry invariants from decorated trees." Abstract
8.04 Arye Juhasz (Technion), "The isoperimetric function of groups defined by a single positive word." Abstract
31.03 - 4.04 workshop Geometry of computation in groups, Erwin Schrödinger International Institute
25.03 Bogdan Nica (Universität Göttingen), "Analytic aspects of boundaries of hyperbolic groups." Abstract
18.03 Adrien Le Boudec (Université Paris-Sud 11), "Tree almost automorphism groups." Abstract
11.03 Chris Cave (University of Southampton), "Coarse embeddability into Hilbert spaces and its consequences." Abstract

Wintersemester 2013/14

28.01 Hiroshi Ando (Erwin Schrödinger Institute), "Finite type Polish groups." Abstract
14.01 Louis Funar (Université de Grenoble I), "On mapping class groups representations." Abstract
7.01 Christopher Cashen (Universität Wien), "Growth Tight Actions." Abstract
17.12 Federico Berlai (Universität Wien), "Residually amenable groups: stability properties." Abstract
10.12 Jakub Gismatullin (Uniwersytet Wroclawski), "Weak sofic and weak hyperlinear groups." Abstract
3.12 François Dahmani (Université Joseph Fourier, Grenoble I), "The conjugacy problem for some automorphisms of free groups, through suspensions." Abstract
19.11 Alessandro Sisto (ETH Zurich), "Random walks and relative hyperbolicity." Abstract
12.11 Rudolf Zeidler (Universität Göttingen), "Coarse median structures." Abstract
5.11 Markus Steenbock (Universität Wien), "Rips construction without unique product." Abstract
29.10 Alexandre Martin (Universität Wien), "Combination of classifying spaces for proper actions." Abstract
22.10 Fabian Haiden (Universität Wien), "Entropy of endofunctors." Abstract
15.10 Romain Tessera (ENS Lyon), "Hausdorff-Gromov limits of rescaled finite transitive graphs." Abstract
2.10 Hans-Jurgen Bandelt (Universität Hamburg), "A mathematical duality and its application in forensic genetics." (Kolloquiumsvortrag) Abstract
2.10 Martino Lupini (York University), "Sofic and hyperlinear groups and the logic for metric structures." Abstract

Sommersemester 2013

18.06 Erik Guentner (University of Hawaii), "A differential complex for CAT(0) cubical spaces" Abstract
11.06 Rufus Willett (University of Hawaii), "Expanders and ghost projections." Abstract
28.05 Ján Špakula (Universität Wien), "Uniformly bounded representations of hyperbolic groups." Abstract
14.05 Hiroki Matui (Chiba University), "Topological full groups of etale groupoids." Abstract
7.05 Federico Berlai (Universität Wien), "Scale function and topological entropy in locally compact totally disconnected groups." Abstract
23.04 Rudolf Zeidler (Universität Wien), "Outer automorphisms of hyperbolic groups with property (T)." Abstract Lecture notes
16.04 Simone Virili (UA Barcelona), "(Co)Hopficity of representations of an infinite group." Abstract
9.04 Yago Antolin (Université  de Neuchâtel), "Automorphisms of groups with hyperbolically embedded subgroups." Abstract
19.03 Ashot Minasyan (University of Southampton), "Hyperbolically embedded subgroups in groups acting on trees and in graph products."Abstract
5.03 Ilya Kazachkov (University of Oxford), "From real trees to real cubings." Abstract

Wintersemester 2012/13

30.01 Liviu Paunescu (Universität Wien), "Linear sofic groups and algebras."Abstract
23.01 Alexandre Martin (Université  de Strasbourg), "Construction of boundaries for non-positively curved complexes of groups."Abstract
9.01 Marc Bourdon (Université  de Lille 1), "Some applications of $\ell_p$-cohomology to boundaries of Gromov hyperbolic spaces."Abstract
12.12 John Mackay (University of Oxford), "Quasi-hyperbolic planes in relatively hyperbolic groups." Abstract
5.12 Victor Chepoi (Université  de la MediterranĂŠe), "Colouring hyperplanes of CAT(0) cube complexes."Abstract
28.11 Christopher Cashen (Universität Wien), "Line patterns and quasi-isometries of graphs of groups." Abstract
21.11 Matthew T. Clay (University of Arkansas), "Turn graphs and extremal surfaces." Abstract
14.11 Jacek Swiatkowski (Uniwersytet Wroclawski), "Topology of the Gromov boundary of free product of hyperbolic groups." Abstract
7.11 Ruth Charney (Brandeis University), "Boundaries of spaces of non-positive curvature." (Kolloquiumsvortrag) Abstract
7.11 Ruth Charney (Brandeis University), "Outer space for right-angled Artin groups." Abstract
31.10 Roger Gomez Ortells (Universität Wien), "On compactly supported cohomology of systolic pseudomanifolds." Abstract
24.10 Tadeusz Januszkiewicz (Polish Academy of Sciences), "A twin of the braid group." (Kolloquiumsvortrag) Abstract
24.10 Tadeusz Januszkiewicz (Polish Academy of Sciences), "Fundamental groups of iterated blowups." Abstract
17.10 Alexandra Pettet (University of British Columbia), "Relative twisting in Outer space."Abstract
10.10 Wolfgang Woess (TU Graz), "Horocyclic products of trees." Abstract

Sommersemester 2012

26.06 Goulnara Arzhantseva (Universität Wien), "Infinitely presented groups satisfying Baum-Connes conjectures." Abstract
12.06 Masato Mimura (Université  de Neuchâtel), "Property (TT)/T and homomorphism superrigidity into mapping class groups." Abstract
5.06 Bernhard Krön (Universität Wien), "Vertex cuts." Abstract
22.05 Swiatoslaw R. Gal (Uniwersytet Wroclawski), "Dynamics, growth of cocycles, and distorted elements." Abstract
15.05 Liviu Paunescu (Universität Wien), "Indecomposable sofic approximations." Abstract
9.05 Henry Segerman (University of Melbourne), "A generalisation of the deformation variety" Abstract
8.05 François Gautero (Université  de Nice), "Gromov's a-T-menability and free-by-free groups." Abstract
24.04 Markus Steenbock (Universität Wien), "Graphical random groups." Abstract
17.04 Fanny Kassel (Université  de Lille 1), "Discrete spectrum of the Laplacian on non-Riemannian locally symmetric spaces." Abstract
29.03 Bruno Benedetti (KTH Stockholm), "Convex triangulations"Abstract
20.03 Cornelia Drutu Badea (Oxford), "Equivalent notions of rank for manifolds of non-positive curvature and for mapping class groups of surfaces."Abstract
13.03 Alessandra Iozzi (ETH Zürich), "Unitary representations" (introductory) and "Multiplicative representations of virtually free groups" Abstract
6.03 Boštjan Brešar and Tanja Gologranc (University of Maribor), "Median graphs, algebras and complexes" Abstract

Wintersemester 2011/12

31.01 Dominik Gruber (Universität Wien), "Graphical small cancellation groups." Abstract
27.01 Alex Gamburd (CUNY), "Generalization of Selberg's 3/16 Theorem and Affine Sieve." Abstract
26.01 Alex Gamburd (CUNY), "Expander Graphs, Thin Groups and Super-strong Approximation." (Kolloquiumsvortrag) Abstract
24.01 François Guéritaud (Université  de Lille 1), "Deforming quotients of rank-one groups." Abstract
17.01 Adam Timar (Universität Wien), "Critical percolation and graph sequences." Abstract
13.12 Valerio Capraro (Université  de Neuchâtel), "Topology on locally finite metric spaces" Abstract
6.12 Adam Timar (Universität Wien), "Quasi-invariant means and Zimmer amenability." Abstract
29.11 Luis Manuel Rivera Martinez (Universität Wien), "Almost commuting matrices and related topics" Abstract
22.11 Damian Osajda (Universität Wien), "A construction of highly dimensional hyperbolic Coxeter groups." Abstract
15.11 Markus Steenbock (Universität Wien), "Torsion-free group without unique product property." Abstract
8.11 Swiatoslaw R. Gal (Universität Wien), "Reflection length on Coxeter groups."Abstract
18.10 Swiatoslaw R. Gal (Universität Wien), "Subgroups of Interval Exchange groups." Abstract
11.10 Adam Timar (Universität Wien), "On the separation profile of infinite graphs."Abstract

Sommersemester 2011

28.06 Goulnara Arzhantseva (Universität Wien), "Introduction to the space of marked groups" and "Finite-dimensional approximations of finitely generated groups."Abstract
21.06 Luis Manuel Rivera Martinez (Universität Wien), "Weakly-sofic groups."Abstract
16.06 Bernhard Krön (Universität Wien), "Linear boundary of finitely generated groups"Abstract
14.06 John S. Wilson (Oxford), "Hereditarily just infinite groups"
7.06 Swiatoslaw R. Gal (Universität Wien), "Groups with matrix models and continous logic." Abstract
31.05 Swiatoslaw R. Gal (Universität Wien), "Groups with matrix models and continous logic." Abstract
24.05 Swiatoslaw R. Gal (Universität Wien), "We take syntax seriously!" Abstract
10.05 Adam Timar (Universität Wien), "Some famous families of groups. Questions related to soficity."
3.05 Adam Timar (Universität Wien), "Ultraproducts and soficity. Surjunctive groups."
12.04 Adam Timar (Universität Wien), "Equivalents of soficity. Basic properties of sofic groups."
5.04 Adam Timar (Universität Wien), "More examples of sofic groups and limit measures. Random trees."
29.03 Adam Timar (Universität Wien), "Basics on the growth of groups and amenability. Limits of graph sequences, a necessary condition for limit graphs"
22.03 Adam Timar (Universität Wien), "Cayley graphs, unimodularity, weak limits of finite graphs"

Wintersemester 2010/11

25.01 Goulnara Arzhantseva (Universität Wien), "Finitely presented random groups are surface-like"Abstract
18.01 Martina Kubitzke (Universität Wien), "The multiplicity conjecture for barycentric subdivisions of simplicial complexes"Abstract
11.01 Myrto Kallipoliti (Universität Wien), "A topological characterization of the plane and homogeneous continua" Abstract
07.12 Wolfgang Alexander Moens (Universität Wien), "A characterisation of nilpotent Lie algebras by their (generalised) derivations"Abstract
30.11 Damian Osajda (Universität Wien), "Fixed point theorem for systolic complexes"Abstract
23.11 Dietrich Burde (Universität Wien), "Groups admitting affine crystallographic actions"Abstract
16.11 Bernhard Krön (Universität Wien), "Linear boundary of finitely generated groups"Abstract
9.11 Swiatoslaw R. Gal (Uniwersytet Wroclawski), "Asymptotic dimension and uniform embeddings"Abstract
12.10 Goulnara Arzhantseva (Universität Wien), "Coarse amenability and coarse embeddings"Abstract
Last updated  August 11, 2017.