Archiv
Hier finden Sie die Listen der Veranstaltungen vergangener Semester:
16.07.2024 (Di) Z21/242 14:00 |
Johannes Dietzschold (Leipzig) The Fitting Lemma for Finite Tracial von Neumann Algebras |
09.07.2024 (Di) Z21/242 15:00 |
Pietro Giavedoni The problem of classification of real Riemann surfaces can be formulated as the challenge to decide if a real Riemann surface - or equivalently, a projective, smooth and irreducible curve - is endowed with real points, based on any "real" period matrix of its. Solved only for genus two (by Comessatti), it has been open for more than one century nowadays. I will propose an exhaustive and effective solution valid for all genera. |
02.07.2024 (Di) Z21/242 15:00 |
kein Seminar |
25.06.2024 (Di) Z21/242 15:00 |
kein Seminar |
18.06.2024 (Di) Z21/242 15:00 |
Lorenzo Baldi (MPI-MIS Leipzig) Given a real projective curve X, we study the dual convex cones of nonnegative forms and positive Borel measures supported on X. For the dual cone of measures, we deduce that the Caratheodory number is determined by the topology of the real locus of the curve, using a technique inspired by Hilbert's proof on ternary quartics. Through the talk, we present some possible future research directions of algebraic and differential nature, to extend our results beyond the genus one case. Based on a joint work with Greg Blekherman and Rainer Sinn. |
11.06.2024 (Di) Z21/242 15:00 |
Jonas Pinke (Bielefeld) Pontryagins famous duality theorem establishes a strong relationship between locally compact abelian hausdorff (LCA) groups and their dual groups, providing deep insights into the structure and behavior of these groups. In the talk we will give a proof of the duality theorem based on ideas from category theory, which is guided by the structure within the category LCA.The duality theorem will first be established for the subcategory of compactly generated abelian Lie-Groups.Through the study of "formal" limits and colimits the duality is expanded to a duality between the subcategories of discrete abelian and compact abelian LCA groups. From there, a study of exact sequences will result in the full duality theorem for the category LCA. |
04.06.2024 (Di) Z21/242 15:00 |
kein Seminar |
28.05.2024 (Di) Z21/242 15:00 |
kein Seminar |
21.05.2024 (Di) | kein Seminar (Pfingstferien) |
14.05.2024 (Di) Z21/242 15:00 |
kein Seminar |
07.05.2024 (Di) Z21/242 15:00 |
kein Seminar |
30.04.2024 (Di) Z21/242 15:00 |
kein Seminar |
23.04.2024 (Di) Z21/242 15:00 |
Jakob Galley (TU Dresden) Topics around the Jacobian Conjecture |
16.04.2024 (Di) Z21/242 15:00 |
kein Seminar |
09.04.2024 (Di) |
Asgar Jamneshan (Koc University, Istanbul) The analogue of the Gowers uniformity norms for measure-preserving abelian actions is the Host-Kra-Gowers seminorms, which are intimately connected to the Host-Kra-Ziegler factors of such systems. The corresponding inverse question, in the dynamical setting, asks for a description of such factors in terms of systems of algebraic origin. In this talk, we present a satisfactory answer to inverse question in the case of the Gowers $U^3$-norm in the combinatorial setting by completely classifying Host-Kra-Ziegler factors of order $2$, also known as Conze-Lesigne factors, for all countable measure-preserving abelian actions. |
30.01.2024 (Di) 15:00 Uhr Z21/242 |
Andreas Thom (TU Dresden) Mixed identities for oligomorphic groups |
23.01.2024 (Di) 15:00 Uhr Z21/241 |
Oliver Sander (TU Dresden) |
16.01.2024 (Di) 15:00 Uhr Z21/242 |
Kyle Gannon (Beijing) Abstract: Given a locally compact topological group, there is a correspondence between idempotent probability measures and compact subgroups. An analogue of this correspondence continues into the model theoretic setting. In particular, if G is a stable group, then there is a one-to-one correspondence between idempotent Keisler measures and type-definable subgroups. The proof of this theorem relies heavily on the theory of local ranks in stability theory. Recently, we have been able to extend a version of this correspondence to the abelian NIP setting. In this context, we prove that generically stable idempotent Keisler measures correspond to fsg subgroups. These results rely on recent work connecting generically stable measures to generically stable types over the randomization. This is joint work with Artem Chernikov and Krzysztof Krupinski. |
09.01.2024 (Di) 15:00 Uhr Z21/242 |
Héctor Sánchez (Leipzig) |
19.12.2023 (Di) 15:00 Uhr Z21/242 |
Martin Keller-Ressel (TU Dresden) Hyperbolic Geometry in Machine Learning and Network Science |
12.12.2023 (Di) 15:00 Uhr Z21/242 |
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05.12.2023 (Di) 15:00 Uhr Z21/242 |
Dimitrii Pavlov (MPI Leipzig) Abstract: A Grasstope is the image of the totally nonnegative Grassmannian $\mathrm{Gr}_{\geq 0}(k,n)$ under a linear map $\mathrm{Gr}(k,n)\dashrightarrow \mathrm{Gr}(k,k+m)$. This is a generalization of the amplituhedron, a geometric object of great importance to calculating scattering amplitudes in physics. The amplituhedron is a Grasstope arising from a totally positive linear map. While amplituhedra are relatively well-studied, much less is known about general Grasstopes. In this talk, I will discuss combinatorics and geometry of Grasstopes in the m=1 case. In particular, I will show that they can be characterized as unions of cells of a hyperplane arrangement satisfying a certain sign variation condition. This is based on joint work with Yelena Mandelshtam and Lizzie Pratt. |
28.11.2023 (Di) 15:00 Uhr Z21/242 |
Hamid Rahkooy (Oxford) |
21.11.2023 (Di) 15:00 Uhr Z21/242 |
Mario Kummer (TU Dresden) Fourier Quasicrystals |
07.11.2023 (Di) 15:00 Z21/242 |
Max Schmidt (TU Dresden) |
24.10.2023 (Di) 15:00 Uhr Z21/242 |
Seminar Geometrie Abstract: Whenever a polynomial arises form another polynomial by substituting zero for some variables, we call the second polynomial an extension of the first one. A real multivariate polynomial is called real zero if it has only real zeros along all lines through the origin. In the main part of this talk, we will show that there are real zero polynomials which do not have a common extension (called amalgam) which is again real zero. Additionally, I will state some cases where real zero amalgams exist and discuss some open problems. (Joint work with Markus Schweighofer.) |
20.09.2023 (Mi) -26.09.2023 (Di) Z21 / room tba. & online (Zoom) |
Graduate Lecture / Compact Course This series of lectures aims at Master's and PhD students in mathematics and offers a first glimpse into topics which are not routinely taught in our MSc/PhD programme. The emphasis is to introduce new concepts and techniques, and not to present full mathematical details. Dr. Cy Maor (Hebrew University of Jerusalem) Non-Euclidean elasticity: thin bodies and material defects Tentative Schedule: |
Sommersemester 2023 (summer term 2023) | |
27.06.2023, 15:00 | Srivatsav Kunnawalkam Elayavalli (Vanderbilt) Survey on free entropy |
20.06.2023, 15:00 |
Adam Humeniuk (Mount Royal University) Abstract: Every non-selfadjoint operator algebra $A$ generates a C*-algebra, but isomorphic copies of $A$ can generate many non-isomorphic C*-algebras, and we call these the C*-covers of $A$. A celebrated result - first proved by Hamana, is that a unique minimum C*-cover for any $A$ exists, called the C*-envelope. The C*-envelope is intrinsic to $A$, but non-isomorphic operator algebras $A$ and $B$ can share the same C*-envelope. If we instead ask that $A$ and $B$ share ALL the same C*-covers, must $A$ and $B$ be isomorphic? There are multiple natural senses in which two operator algebras may have "the same" C*-covers, and we will discuss how these different senses remember different information about the operator algebras involved. |
23.05.2023, 15:00 |
Raluca Vlad (Brown University) Abstract: A canonical curve of genus g and degree 2g-2 is a genus g curve considered under its canonical embedding into P^{g-1}. A general hyperplane section X of such a curve consists of 2g-2 points. We study the configurations of points that arise in this way. To such a configuration X of 2g-2 points, we associate a matroid that encodes the linear dependencies of these points. It is a consequence of the Riemann-Roch theorem that the matroid we obtain is self-dual, in the sense that a subset D of X of size g-1 is linearly dependent if and only if its complement X\D is also dependent. I will go into details about the special case of graph curves, which are sets of 2g-2 lines in P^{g-1}, with each line intersecting three others transversely. In this case, the matroid associated to a general hyperplane section of a graph curve depends only on the graph associated to the curve. |
16.05.2023, 15:00 |
Clemens Brüser (TUD) Abstract: In this talk, I will present our work on the study of determinantal representations of globally nonnegative polynomials. We ask whether for a given polynomial p that is globally nonnegative, there exists a symmetric matrix M, the entries of which are quadratic forms of degree 2 such that
For suitable polynomials p in three variables, we can answer this question in a hands-on fashion: Assuming that such a determinantal representation M exists, it defines a morphism of sheaves. The cokernel of this map can be explicitly described using methods of cohomology. This allows for verification whether M in the assumed form exists and - provided the answer is positive - a reconstruction of M. |
25.04.2023, 15:00 | Andreas Thom (TUD)
Common transversals for subgroups Abstract: I will give a talk about an ongoing project with Hiroshi Ando. We study the problem, when a subgroup of a group admits a subset, which is a set of representatives of left cosets and right cosets at the same time. |
04.04.2023, 15:00 |
Chieu Minh Tran (NSU) Abstract: Let SO(3,R) be the 3D-rotation group equipped with the real-manifold topology and the normalized Haar measure \mu. Confirming a conjecture by Breuillard and Green, we show that if A \subseteq SO(3,R) is open and has sufficiently small measure, then \mu(A^2) > 3.99 \mu(A). We also show a more general result for the product of two sets, which can be seen as a Brunn-Minkowski-type inequality for sets with small measure in SO(3,R). (Joint with Yifan Jing and Ruixiang Zhang) |
29.09.2022, 15:00 | Alessandro Carderi (Karlsruhe) |
18.10.2022, 15:00 | Jan Boschheidgen (Madrid) Non-convergence of eigenvalue measures associated to groups |
01.11.2022 15:00 | Helmut Schießel (Dresden) DNA: Euler elasticas and graphs |
08.11.2022 15:00 |
Max Illmer (Innsbruck) |
15.11.2022 15:00 |
Stefan Drigalla (Dresden) |
22.11.2022 15:00 | Alon Dogon (Weizman Institute)
"Flexible Hilbert-Schmidt stabilty and hyperlinearity" |
29.11.2022 15:00 | Stefan Drigalla (Dresden) Geometric property (T) and sofic approximations II |
06.12.2022 15:00 |
Patrick Serwene (TU Dresden) |
31.01.2023 15:00 |
Sebastian Debus |
09.04.2019 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie |
16.04.2019 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Jakob Schneider, TU Dresden Isomorphism questions for metric ultraproducts of finite quasisimple groups |
14.05.2019 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Henning Krause, Universität Bielefeld Cauchy completions and perfect complexes |
21.05.2019 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Françoise Point, Institut de Mathématiques de Jussieu On pseudo-finite groups |
18.06.2019 (Di) 15:00 Uhr WIL A 120 |
Graduate Lectures Patrick Jaap TU Dresden, Institut für Numerische Mathematik On plastic deformation: From physics over convex analysis to numerical simulation (1/3) Poster mit Abstract |
25.06.2019 (Di) 15:00 Uhr WIL A 120 |
Graduate Lectures Patrick Jaap TU Dresden, Institut für Numerische Mathematik On plastic deformation: From physics over convex analysis to numerical simulation (2/3) Poster mit Abstract |
02.07.2019 (Di) 15:00 WIL A 120 |
Graduate Lectures Patrick Jaap TU Dresden, Institut für Numerische Mathematik On plastic deformation: From physics over convex analysis to numerical simulation (3/3) Poster mit Abstract |
23.07.2019 (Di) 15:00 Uhr WIL A 124 |
Graduate Lectures Hans Christian Herbig Universidade Federal do Rio de Janeiro Real and complex algebraic geometry of Hamiltonian reductions I Poster & Abstract Ansprechpartner: Prof. Dr. U. Krähmer |
24.07.2019 (Di) 15:00 Uhr WIL A 124 |
Graduate Lectures Real and complex algebraic geometry of Hamiltonian reductions II Poster & Abstract Ansprechpartner: Prof. Dr. U. Krähmer |
25.07.2019 (Di) 15:00 Uhr WIL A 124 |
Graduate Lectures Real and complex algebraic geometry of Hamiltonian reductions III Poster & Abstract Ansprechpartner: Prof. Dr. U. Krähmer |
Classical Galois theory of fields (as met in an undergraduate course) was generalised to commutative rings around 1960 by Auslander, Goldman, Chase, Harrison and Rosenburg. Around the same time, Grothendieck developed the theory of etale coverings of schemes and gave a more geometric view. In the ensuing half century the general framework has been expanded to many more settings including derived algebra. This talk will discuss the basic ideas that are common to these.
I will review the step from the field theory version to commutative rings, pointing out some of the extra tools required. If there is time I will explain some features of a derived version (originally developed in a topological context by Rognes).
16.04.2019, 15:00, WIL A 120: Seminar Geometrie
Jakob Schneider, TU Dresden: Isomorphism questions for metric ultraproducts of finite quasisimple groups
We compute double centralizers of semisimple torsion elements in metric ultraproducts of finite quasisimple groups. This information is used to show that (up to the exception:
Sp_{U}(q)=GO_{U}(q)?) the Lie type and the field size, is an invariant which is determined by the group structure of such an ultraproduct.
21.05.2019, 15:00, WIL A 120: Seminar Geometrie
Françoise Point, Institut de Mathématiques de Jussieu: On pseudo-finite groups
First I will introduce the notion of being pseudo-C for a class C of groups. For the class of finite groups, I will relate it to other notions of approximability.
Then I will review results on one hand on a question of G. Sabbagh: are there infinite finitely generated pseudo finite groups and on the other hand on analogs of Tits alternative for certain classes of pseudo-finite groups.
09.10.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar |
23.10.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Lukas Gohla, TU Dresden On Margulis' Normal Subgroup Theorem for groups and equivalence relations |
13.11.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Sebastian Halbig, TU Dresden Hopf algebras with and without modular pairs in involution |
27.11.2018 (Tue) 15:00 WIL A 120 |
Graduate Lectures in Mathematics Alessandro Carderi TU Dresden, Institut für Geometrie An introduction to machine learning I Poster und Abstract |
04.12.2018 (Tue) 15:00 WIL A 120 |
Graduate Lectures in Mathematics Alessandro Carderi TU Dresden, Institut für Geometrie An introduction to machine learning II Poster und Abstract |
11.12.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Jitendra Bajpai, Universität Göttingen Arithmeticity and Thinness of hypergeometric groups |
18.12.2018 (Tue) 15:00 WIL A 120 |
Graduate Lectures in Mathematics Alessandro Carderi TU Dresden, Institut für Geometrie An introduction to machine learning II Poster und Abstract |
15.01.2019 (Tue) 15:00 WIL A 120 |
Seminar Geometrie Moritz Weber, Uni Saarbrücken Quantum symmetries of finite graphs (Abstract) |
22.01.2019 (Tue) 15:00 WIL A 120 |
Graduate Lectures in Mathematics Carina Geldhauser TU Dresden, Institut für Wissenschaftliches Rechnen An Introduction to Stochastic Partial Differential Equations I |
29.01.2019 (Tue) 15:00 WIL A 120 |
Graduate Lectures in Mathematics Carina Geldhauser TU Dresden, Institut für Wissenschaftliches Rechnen An Introduction to Stochastic Partial Differential Equations II |
05.02.2019 (Tue) 15:00 WIL A 120 |
Graduate Lectures in Mathematics Carina Geldhauser TU Dresden, Institut für Wissenschaftliches Rechnen An Introduction to Stochastic Partial Differential Equations III |
15.01.2019 (Fri) 13:30 WIL A 120 |
Seminar Geometrie Nir Lazarovich, ETH Zürich Flexible Stability of Surface Groups |
In classical semi-algebraic geometry one is interested in the study of
special subsets of the euclidean space: the semi-algebraic sets. Roughly
speaking, these are sets that can be defined by polynomial equalities
and inequalities as well as boolean combinations. One of the most
important results about semi-algebraic sets is the Projection Theorem:
Every linear projection of a semi-algebraic set is again semi-algebraic.
From the perspective of mathematical logic, this theorem implies that
the theory of real closed fields has quantifier elimination.
Triggered by applications in a variety of different areas a new branch
of the theory has emerged: the free semi-algebraic geometry. The basic
idea is to consider tuples of matrices instead of tuples of numbers.
Because the free theory generalizes the classical one, the question is
whether some important classical properties like the Projection Theorem
can be transferred to the free setup.
In the talk we will point out the limits of a free quantifier
elimination theorem and show an approach for a weak version of a free
projection theorem.
A modular pair in involution of a Hopf algebra H is a pair consisting of a grouplike element g in H and a character f on H such that f(g) = 1 and the antipode square is given by the adjoint action of g and f. The ground field k of H can be viewed as a module and a comodule via the character and the grouplike, respectively. The module comodule k is then a stable anti-Yetter-Drinfeld module playing the role of coefficients in Hopf-cyclic cohomology introduced by Connes and Moscovici. When H is finite dimensional, the aforementioned antipode condition for (g,f) is a square root of the celebrated Radford formula for the 4th power of the antipode, and is thus related to the work of Radford and Kauffman concerning the existence of a ribbon element in the Drinfeld double of H.
Using Radford's biproduct (also known as Majid's bosonization) of certain Nichols algebras over cyclic groups, we construct finite-dimensional Hopf algebras that do not admit a modular pair in involution.
10.04.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar |
17.04.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Tom Kaiser, Université de Neuchâtel Sofic approximations and property A |
24.04.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Francesca Arici, MPI for Mathematics in the Sciences Circle and sphere bundles in noncommutative geometry |
09.05.2018 (Tue) 15:00 WIL A 120 |
Seminar Geometrie Ulrich Krähmer, TU Dresden Mixed vs cyclic homology |
15.05.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Michael Whittaker, University of Glasgow New directions in self-similar group theory |
29.05.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Manuel Martins, TU Dresden The nodal cubic is a quantum homogeneous space |
05.06.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar David Kyed, Syddansk Universitet Measure equivalence for locally compact groups |
12.06.2018 (Tue) 15:00 WIL A 120 |
Graduate Lectures Maxime Gheysens, TU Dresden On, around, and beyond Ryll-Nardzewski's theorem I |
19.06.2018 (Tue) 15:00 WIL A 120 |
Graduate Lectures Maxime Gheysens, TU Dresden On, around, and beyond Ryll-Nardzewski's theorem II |
25.06.2018 (Mon) 15:00 WIL A 317 |
Geometry Seminar
Alexander Kuklev, JetBrains Research |
26.06.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar
Alexander Kuklev, JetBrains Research |
02.07.2018 (Mon) 15:00 WIL A 317 |
Geometry Seminar
Alcides Buss, Federal University of Santa Catarina, Florianópolis |
03.07.2018 (Tue) 15:00 WIL A 120 |
Graduate Lectures Maxime Gheysens, TU Dresden On, around, and beyond Ryll-Nardzewski's theorem III |
10.07.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Henry Bradford, Georg-August-Universität Göttingen On LEF Growth in Groups |
17.07.2018 (Tue) 15:00 WIL A 120 |
Geometry Seminar Madeleine Jotz Lean, Georg-August-Universität Göttingen Ideals in Lie algebroids and the Atiyah class |
10.04.2018, 15:00, WIL A 120: Seminar Geometrie
Niels Kowalzig, Sapienza Università di Roma: Higher brackets on cyclic and negative cyclic (co)homology
In this talk, we will embed the string topology bracket developed by Chas-Sullivan and Menichi on negative cyclic cohomology groups as well as the dual bracket found by de Thanhoffer de Voelcsey-Van den Bergh on negative cyclic homology groups into the global picture of a noncommutative differential (or Cartan) calculus up to homotopy on the (co)cyclic bicomplex in general, in case a certain Poincare' duality is given. For negative cyclic cohomology, this in particular leads to a Batalin-Vilkovisky algebra structure on the underlying Hochschild cohomology. In the special case in which this BV bracket vanishes, one obtains an e_{3}-algebra structure on Hochschild cohomology. The results are given in the general and unifying setting of (opposite) cyclic modules over (cyclic) operads.
17.04.2018, 15:00, WIL A 120: Seminar Geometrie
Tom Kaiser, Université de Neuchâtel: Sofic approximations and property A
Consider a residually finite group, then given a filtration we can construct the box space of this group with respect to the chosen filtration. It is a known result that the box space having property A is equivalent to the group being amenable. The same is true for hyperfiniteness. Firstly we will optimise this result by replacing filtrations by Farber sequences and secondly determine which arrows still hold when we replace box spaces by sofic approximations.
Knowledge of the above concepts is not required since these will be introduced during the talk.
24.04.2018, 15:00, WIL A 120: Seminar Geometrie
Francesca Arici, MPI for Mathematics in the Sciences Circle and sphere bundles in noncommutative geometry
In this talk I will recall how Pimsner algebras of self Morita equivalences can be thought of as total spaces of quantum circle bundles, and the associated six term exact sequence in K-theory can be interpreted as an operator algebraic version of the classical Gysin sequence for circle bundles. After reviewing some results in this direction, I will report on work in progress concerning the construction of higher dimensional quantum sphere bundles in terms of Cuntz-Pimsner algebras of sub-product systems. Based on (ongoing) joint work with G. Landi and J. Kaad.
08.05.2018, 15:00, WIL A 120: Seminar Geometrie
Ulrich Krähmer, TU Dresden: Mixed vs cyclic homology
In this talk I will (try to) explain the main result of the paper I have written with Dylan Madden. Therein, we consider so-called mixed complexes, that is, graded vector spaces C together with linear maps b and d on them such that (C,b) is a chain complex and (C,d) is a cochain complex. One can then consider the homology of the former and the cohomology of the latter, but there is also a way to define a mixed homology that involves both b and d at the same time, and to develop the general theory of such mixed homology group is the aim of the game. Two important examples are given by the differential forms on an oriented Riemannian manifold with the de Rham differential and codifferential as d and b, and the Hochschild chains of an associative algebra.
15.05.2018, 15:00, WIL A 120: Seminar Geometrie
Michael Whittaker, University of Glasgow: New directions in self-similar group theory
A self-similar group (G,X) consists of a group G acting faithfully on a homogeneous rooted tree such that the action satisfies a self-similarity condition. In this talk I will generalise the above definition to faithful groupoid actions on the path space of more general graphs. This new definition allows us to work out the structure of the KMS state space of associated Toeplitz and Cuntz-Pimsner algebras. This is joint work with Marcelo Laca, Iain Raeburn, and Jacqui Ramagge.
29.05.2018, 15:00, WIL A 120: Seminar Geometrie
Manuel Martins, TU Dresden: The nodal cubic is a quantum homogeneous space
Starting from the classical point of view, the notion of quantum homogeneous space will be introduced. The coordinate ring of the nodal cubic in the plane yields such an example, whose corresponding coalgebra Galois extension is expressed in terms of quantum groups at roots of unity and is shown to be cleft.
05.06.2018, 15:00, WIL A 120: Seminar Geometrie
David Kyed, Syddansk Universitet: Measure equivalence for locally compact groups
In the talk I will discuss the notion of measure equivalence within the framework of locally compact second countable groups, with particular emphasis on the unimodular case, and explain how classical results, such as the Ornstein-Weiss theorem, generalize to this setting. If time permits, I will also discuss the notion of uniform measure equivalence and its relation to coarse equivalence. The talk is based on joint work with Juhani Koivisto and Sven Raum.
12.06.2018, 15:00, WIL A 120: Graduate Lectures
Maxime Gheysens, TU Dresden: On, around, and beyond Ryll-Nardzewski's theorem I
After recalling some facts about group actions and functional analysis, we will state and prove Ryll-Nardzewski's theorem.
19.06.2018, 15:00, WIL A 120: Graduate Lectures
Maxime Gheysens, TU Dresden: On, around, and beyond Ryll-Nardzewski's theorem II: Applications
The second lecture will focus on applications of Ryll-Nardzewski's theorem. We will cover in details the existence of Haar measures for compact groups and the unbounded vs. fixed-point dichotomy for isometric actions on reflexive Banach spaces. Other consequences (for instance, for von Neumann algebras or for compactifications of groups) will be mentioned, according to the interest of the audience.
02.07.2018, 15:00, WIL A 317: Geometry Seminar
Alcides Buss, Federal University of Santa Catarina, Florianópolis:
Exotic crossed products of group actions
Motivated by exactness obstructions to the Baum-Connes conjecture with coefficients in C*-algebras, Baum, Guentner and Willett recently introduced a new formulation of the conjecture that replaces the reduced crossed product by the smallest exact crossed product functor. In this talk I will present a more concrete description of this functor that shows, among other things, that the reformulated conjecture coincides with the original one for trivial coefficients. I also intend to present a “dual" construction of the largest injective crossed product functor and explain some interesting connections to exactness and local lifting properties of groups.
03.07.2018, 15:00, WIL A 120: Graduate Lectures
Maxime Gheysens, TU Dresden: On, around, and beyond Ryll-Nardzewski's theorem III: Sibling theorems
We will explain three interesting related theorems: a fixed-point theorem for L^{1}-spaces (an unexpected application of Ryll-Nardzewski's theorem), a fixed-point theorem for actions on convex cones (a generalisation thereof), and the Day–Rickert characterization of amenability (which shows that Ryll-Nardzewski's theorem is somehow optimal).
10.07.2018, 15:00, WIL A 120: Geometry Seminar
Henry Bradford, Georg-August-Universität Göttingen: On LEF Growth in Groups
In this talk I will propose a quantitative version of the LEF (local embeddability into finite groups) property. I will estimate this new invariant in some examples, and compare it with existing invariants which quantify residual finiteness and soficity. I will give a construction of a family of finitely generated residually finite groups which nevertheless admit many more local embeddings to finite groups than they do finite quotients. It would be of great interest to identify more groups satisfying this last property since, as I shall show, such groups are never finitely presentable.
17.07.2018, 15:00, WIL A 120: Geometry Seminar
Madeleine Jotz Lean, Georg-August-Universität Göttingen: Ideals in Lie algebroids and the Atiyah class
I will describe a notion of ideals in Lie algebroids, named
'infinitesimal ideal systems' and motivate from several point of views
why this is in my opinion the 'right' notion of symmetry in the Lie
algebroid setting: I will discuss quotients by infinitesimal ideal
systems, their equivalence to multiplicative foliations on Lie
groupoids, and how they define sub-representations of Lie algebroid adjoint
representations (up to homotopy).
Then I will talk about the Atiyah class of an infinitesimal ideal system and give an
obstruction to the existence of an ideal system structure on a Lie pair.
This is partly based on joint work with Ortiz and Drummond.
24.10.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Vladimir Finkelshtein, Universität Göttingen Diophantine approximation problems for groups of toral automorphisms |
07.11.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie |
14.11.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Maria Gerasimova, TU Dresden Geometric aspects of unitarisability of discrete groups |
21.11.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Marco Matassa, Université Blaise Pascal – Clermont-Ferrand II Regularity of twisted spectral triples and pseudodifferential calculi |
28.11.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Markus Steenbock, ENS Paris Product Set Growth in Hyperbolic Geometry |
05.12.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Igor Burban, Universität zu Köln Algebraic geometry of the classical Yang-Baxter equation |
12.12.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dominik Gruber, ETH Zürich Hyperbolicity in graphical small cancellation monsters |
09.01.2018 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Tim de Laat, Universität Münster Superexpanders from group actions on compact manifolds |
16.01.2018 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Chiara Esposito, Universität Würzburg Formality and Universal deformation formulas |
23.01.2018 (Di) |
Seminar Geometrie Masato Mimura, EPFL Upgrading fixed points without bounded generation |
30.01.2018 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Christian Voigt, University of Glasgow A deformation of the Baum–Connes assembly map |
13.02.2018 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Anton Claußnitzer, TU Dresden Aspects of p-adic operator algebras |
24.10.2017, 15:00, WIL A 120: Seminar Geometrie
Vladimir Finkelshtein, Universität Göttingen: Diophantine approximation problems for groups of toral automorphisms
I will present sharp rates for a shrinking target problem for the action of arbitrary subgroups of SL(2,Z) on the 2-torus. This can also be viewed as a noncommutative Diophantine approximation problem. The methods require construction of spectrally optimal random walks on groups acting properly cocompactly on Gromov hyperbolic spaces. Additionally, I will explain how similar estimates for this problem in higher dimension can be obtained using harmonic analysis.
07.11.2017, 15:00, WIL A 120: Seminar Geometrie
Mario Kummer, Max-Planck-Institut für Mathematik in den Naturwissenschaften, Leipzig: Interlacing Ehrhart Polynomials of Reflexive Polytopes
There are constructions that associate to a graph a lattice polytope. Furthermore, for each lattice polytope there is the Ehrhart polynomial that computes the number of lattice points in dilations of the polytope. Recently, the roots of Ehrhart polynomials became an object of intensive studies. For many graphs these roots have a remarkable property: They all have real part –1/2. Still, proving that this property holds for a family of graphs is often very hard. One of the first positive results was the case of the complete (1,n)-bipartite graphs proved independently by Kirschenhofer, Pethö and Tichy and by Bump, Choi, Kurlberg and Vaaler. The latter studied this family of polynomials in the context of the local Riemann hypothesis. We prove several conjectures confirming that certain families of polynomials have real part –1/2. The main ingredient is the theory of interlacing polynomials.
14.11.2017, 15:00, WIL A 120: Seminar Geometrie
Maria Gerasimova, TU Dresden: Geometric aspects of unitarisability of discrete groups
A discrete group Γ called unitarisable if for every uniformly bounded representation π: Γ → B(H) of Γ on some Hilbert space H there exists an operator S ∈ B(H) such that S^{-1}π(g)S is unitary for all g ∈ Γ. It is well-known that amenable groups are unitarisable, but it is still unknown if unitarisable groups are amenable.
We will define some analytic characteristic of a group Γ which on one hand is related to unitarisability and on the other hand – to some geometry of Γ. More precisely, it is related to the behaviour of Cayley graphs of Γ when one increases the generating sets. We will also discuss some corollaries of this connection, for example, about the number of colours one need to colour the Cayley graphs of some groups (e.g. for Burnside groups B(m,n)).
21.11.2017, 15:00, WIL A 120: Seminar Geometrie
Marco Matassa, Université Blaise Pascal – Clermont-Ferrand II: Regularity of twisted spectral triples and pseudodifferential calculi
We investigate the regularity condition for twisted spectral triples. This condition is equivalent to the existence of an appropriate pseudodifferential calculus compatible with the spectral triple. A natural approach to obtain such a calculus is to start with a
twisted algebra of abstract differential operators, in the spirit of Higson. Under an appropriate algebraic condition on the twisting, we obtain a pseudodifferential calculus which admits an asymptotic expansion, similarly to the untwisted case. We present some examples coming from the theory of quantum groups. Finally we discuss zeta functions and the residue (twisted) traces on differential operators.
28.11.2017, 15:00, WIL A 120: Seminar Geometrie
Markus Steenbock, ENS Paris: Product Set Growth in Hyperbolic Geometry
Improving a theorem of Razborov (Ann. of Math. 2014), Safin (Mat. Sb. 2011) proved that there is a constant α > 0 such that the cardinality of any finite subset U of a free group that does not generate a cyclic subgroup satisfies |U^{3}| ⩾ α |U^{2}|. In addition, the growth of the cardinalities of the sets U^{n} satisfies U^{n }⩾ α^{n} |U|^{⌊(n+1)/2⌋} for all natural numbers n.
We will discuss the extension of this result to hyperbolic groups. This includes cocompact Fuchsian groups, fundamental groups of compact Riemannian manifolds of negative sectional curvature, and finitely presented small cancellation groups.
05.12.2017, 15:00, WIL A 120: Seminar Geometrie
Igor Burban, Universität zu Köln: Algebraic geometry of the classical Yang-Baxter equation
In my talk, based on a joint work with Lennart Galinat, I am going to give a short introduction into the theory the classical Yang-Baxter equation. Then I shall explain how solutions of this equation can be canonically obtained from appropriate sheaves of Lie algebras on possibly singular Weierstraß cubics.
12.12.2017, 15:00, WIL A 120: Seminar Geometrie
Dominik Gruber, ETH Zürich: Hyperbolicity in graphical small cancellation monsters
Infinitely presented small cancellation groups are a major source of examples and counterexamples in the theory of infinite groups.
Gromov's graphical small cancellation theory is a generalization of classical small cancellation theory that has provided the only known groups with expander graphs embedded in their Cayley graphs, the so-called Gromov's monsters. In my talk, I will discuss advances in understanding features of negative curvature of infinitely presented graphical small cancellation groups, such as admitting interesting actions on Gromov hyperbolic spaces. As an application, I will present a whole new small cancellation theory in varieties of n-periodic groups.
This is based on joint works with multiple co-authors.
09.01.2018, 15:00, WIL A 120: Seminar Geometrie
Tim de Laat, Universität Münster: Superexpanders from group actions on compact manifolds
Expanders are sequences of finite highly connected sparse graphs with an increasing (and unbounded) number of vertices. It is well known that expanders do not coarsely embed into Hilbert spaces. It is a deep open problem whether every expander is a superexpander, i.e. whether all expanders do not coarsely embed into any superreflexive Banach space. In this talk, I will explain a couple of constructions of superexpanders, focusing on the recent constructions coming from certain group actions on compact manifolds.
16.01.2018, 15:00, WIL A 120: Seminar Geometrie
Chiara Esposito, Universität Würzburg: Formality and Universal deformation formulas
In this talk we present an application of formality of Lie algebroids to the case where we have an infinitesimal Poisson action on a manifold M to obtain a generalization of the Drinfeld twists approach to the problem of quantization of symmetries. In particular we obtain a generalized notion of quantum action that yields universal deformation formulas. This is a joint work with N. de Kleijn.
23.01.2018, 15:00, WIL A 120: Seminar Geometrie
Masato Mimura, École polytechnique fédérale de Lausanne: Upgrading fixed points without bounded generation
A natural question on group actions asks the following. "Suppose that an isometric group action on a metric space admits fixed points for certain (small) subgroups. Under which conditions, can we 'upgrade' them to the existence of fixed points for a bigger subgroup, ultimately, for the whole group?"
This question for actions on Hilbert spaces has strong connection to proving Kazhdan's property (T) from relative properties. In 1999 and 2006, Shalom answered it based on (BG) ("Bounded Generation"). I will present the first solution to a natural question from Shalom's work that asks whether we can upgrade fixed points (in an intrinsic way) without employing (BG).
30.01.2018, 15:00, WIL A 120: Seminar Geometrie
Christian Voigt, University of Glasgow: A deformation of the Baum–Connes assembly map
(joint with A. Monk)
A central theme in the study of K-theory of operator algebras is the Baum-Connes conjecture, which predicts the K-theory of group C*-algebras and crossed products. In the case of complex semisimple Lie groups like SL(n,ℂ), the conjecture can be reformulated as saying that a certain deformation induces an isomorphism in K-theory.
In this talk I’ll first review these constructions and results, and then explain a similar picture for complex semisimple quantum groups. These quantum groups can be viewed as deformations of classical complex semisimple groups; on a technical level they are obtained using the Drinfeld double construction. In particular, I’ll show how to obtain an analogue of the Baum-Connes assembly map in this setting. The quantum assembly map is an isomorphism, and it contains the classical Baum-Connes assembly map as a direct summand. I’ll also discuss how the various deformations involved fit together in a conceptual way.
13.02.2018, 15:00, WIL A 120: Seminar Geometrie
Anton Claußnitzer, TU Dresden: Aspects of p-adic operator algebras
In my talk, I define possible p-adic analogues of certain well-known functional analytic concepts such as Hilbert spaces, Banach algebras and group von Neumann algebras. As an example, I will talk about several p-adic Lück type approximation lemmas for residually finite groups.
21.03.2017 (Di) 11:00 Uhr WIL B 113 |
Seminar Geometrie Rahel Brugger, Universität Göttingen Invariant random positive definite functions |
28.03.2017 (Di) 11:00 Uhr WIL B 113 |
Seminar Geometrie Kristin Courtney, University of Virginia Residual f.d. properties of C*-algebras |
30.03.2017 (Di) 11:00 Uhr WIL B 113 |
Seminar Geometrie Lucia Rotheray, University of Glasgow Hopf algebras and Dyson–Schwinger equations |
04.04.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie |
18.04.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Jordan Venters, Warwick, UK Combinatorial Nullstellensatz |
18.04.2017 (Di) 16:30 Uhr WIL B 122 |
Seminar Geometrie Peter Patzt, Freie Universität Berlin Representation stability for filtrations of Torelli groups |
02.05.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie |
09.05.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Anastasia Khukhro, Université de Neuchâtel Geometry of finite quotients of groups |
16.05.2017 (Di) 15:00 Uhr WIL A 120 |
Graduate Lectures Jan Hladky, TU Dresden |
23.05.2017 (Di) 15:00 Uhr WIL A 120 |
Graduate Lectures Jan Hladky, TU Dresden |
30.05.2017 (Di) 15:00 Uhr WIL A 120 |
Graduate Lectures Jan Hladky, TU Dresden |
13.06.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Stefan Kolb, University of Newcastle Braided module categories via quantum symmetric pairs |
21.06.2017 (Mi) 17:00 Uhr WIL C 129 |
Seminar Geometrie Martín Miglioli Geometric aspects of similarity problems |
27.06.2017 (Di) 15:20 Uhr WIL A 120 |
Seminar Geometrie Angela Tabiri, University of Glasgow The nodal cubic is a quantum homogeneos space |
11.07.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Elmar Wagner, Michoacan University of Saint Nicholas of Hidalgo Dirac operator on noncommutative Toeplitz torus |
19.09.2017 (Di) |
Diplomverteidigung Juliane Döring, TU Dresden Karten vom Typ {4, 4} auf dem Torus und der Kleinschen Flasche |
04.04.2017, 15:00, WIL A 120: Seminar Geometrie
Marcus de Chiffre, TU Dresden: Uniformity norms, inverse theorems and ε-representations for amenable groups
The Gowers uniformity norms ‖ ⋅ ‖_{Uk} were originally defined for functions φ : G → ℂ from a finite cyclic (or abelian) group G as part of Gowers' work on arithmetic progressions. Recently Gowers and Hatami extended the definition of the norm ‖ ⋅ ‖_{U2} to maps φ : G → 𝕄_{n} from a general finite group G taking values in the n × n -matrices 𝕄_{n} . Using this definition, they stated and proved a so-called inverse theorem for the U^{2} -norm and, as a corollary, proved a stability result for ε-representations. In this talk, we present an operator algebraic approach to the proof of these theorems, which enables us to extend the definition and results to maps φ : G → ℳ from an amenable group G into a von Neumann algebra ℳ .
18.04.2017, 15:00, WIL A 120: Seminar Geometrie
Jordan Venters, University of Warwick: Combinatorial Nullstellensatz
Many problems in combinatorics may be rephrased as questions about polynomials and in particular the zeroes of these polynomials, one powerful tool in this direction is the combinatorial Nullstellensatz developed by Noga Alon which gives us conditions under which a polynomial restricted to some set is not the zero polynomial.
I will state the combinatorial Nullstellensatz and give several quick applications of it to additive number theory and graph theory.
18.04.2017, 16:30, WIL B 122: Seminar Geometrie
Peter Patzt, Freie Universität Berlin: Representation stability for filtrations of Torelli groups
The notion of representation stability for the symmetric groups, the general linear groups and the symplectic groups was introduced by Church-Farb. In this talk, we give a criterion for a sequence of algebraic representations of the general linear groups to be representation stable. We use this to prove that the factors of the lower central series of the Torelli subgroups of the automorphism groups of free groups are representation stable.
02.05.2017, 15:00, WIL A 120: Seminar Geometrie
Friedrich Wagemann, Université de Nantes: Shelves in algebra and topology
This will be a survey talk about shelves in algebra and topology. A shelf is a set X with a product "<" such that for all x,y,z in X: (x<y)<z = (x<z)<(y<z) (selfdistributivity). This is an instance of the third Reidemeister move, so there are natural applications to knot invariants. To mention just one other application in Lie theory, in case X is a pointed manifold and "<" is smooth, it makes sense to derive (x,y) -> x<y with respect to x and y at the point 1. This gives a Leibniz bracket on the tangent space at 1, and one may ask conversely whether all Leibniz algebras integrate to such shelves. In joint work with Martin Bordemann, we have constructed an integration process which gives back the conjugation shelf underlying a Lie group in case the Leibniz algebra was a Lie algebra.
09.05.2017, 15:00, WIL A 120: Seminar Geometrie
Anastasia Khukhro, Université de Neuchâtel: Geometry of finite quotients of groups
Geometric properties of a collection of finite quotients of a group can provide information about the group if the set of finite quotients is sufficiently rich. Using a metric space constructed using Cayley graphs of these finite quotients, one can exploit the connections between the world of group theory and graph theory to give examples of metric spaces with interesting and often surprising properties. In this talk, we will describe some results in this direction, and then give recent results concerning geometric rigidity of finite quotients of a group (joint work with Thiebout Delabie).
16.05, 23.05, 30.05.2017, 15:00, WIL A 120: Graduate Lectures
Jan Hladky, TU Dresden: Szemerédi regularity lemma and its applications
In 1978, Szemerédi published a three page paper "Regular partitions of graphs". The result of that paper, now known as the Regularity lemma, became one of the most important tools in graph theory, with deep connections to other parts of combinatorics, number theory, and to theoretical computer science.
The first lecture will cover the concept of graph quasirandomness and the Regularity lemma. We shall also derive the Removal lemma. In the second lecture, we will give applications to extremal graph theory, property testing, and number theory. In the third lecture, we shall use the Regularity lemma to construct graphons which are the key objects of the theory of limits of dense graphs.
13.06.2017, 15:00, WIL A 120: Seminar Geometrie
Stefan Colb, University of Newcastle: Braided module categories via quantum symmetric pairs
Abstract: In the early 90s V. Turaev and N. Reshetikhin formulated a
graphical calculus for invariants of knots and links. This calculus is
based on the notion of a ribbon category, which is a braided monoidal
category with some additional structure (twist and duality). Categories of
representations of quantum groups provide an important example for this
theory.
The Reshetikhin-Turaev calculus can be extended to braided module
categories over ribbon categories. In this talk I will explain the notion
of a braided module category and discuss its incarnation via
quasitriangular coideal subalgebras. I will then outline how quantum group
analogs of symmetric spaces provide examples of braided module categories.
21.06.2017, 17:00: Seminar Geometrie
Martín Miglioli, Instituto Argentino de Matemática: Geometric aspects of similarity problems
Abstract: Some similarity problems study conditions under which a unital homomorphism between operator algebras is conjugated to a self-adjoint homomorphism. We study aspects of these problems through the isometric action of the invertible elements of a C*-algebra on the positive invertible elements given by g.a=gag*. Minimality properties of projections to closed convex sets in the non-positively curved cone of positive invertible operators are used to study minimality properties of canonical orthogonalizers of some unital algebra homomorphisms. The convexity of the distance along geodesics is used to prove interpolation results of norms of conjugated representations. We also address the question of existence of unitarizers of groups of invertible operators when these groups act on manifolds of positive invertible operators endowed with a metric derived from a trace. Here the Bruhat–Tits fixed point theorem is used to show that the square root of the circumcenter of orbits are unitarizers of the groups.
25.01-26.01.17 WIL C 307 |
Symposium Konvex- und Diskrete Geometrie |
17.01.2017 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Maxime Gheysens, Lausanne, Switzerland Hilbert spaces can affinely spot amenability |
25.10.2016 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie - Verteidigung Masterarbeit |
01.11.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Christian Becker, TU Dresden Surfaces, Groups and Gauge Fields I |
08.11.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Christian Becker, TU Dresden Surfaces, Groups and Gauge Fields II |
15.11.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Christian Becker, TU Dresden Surfaces, Groups and Gauge Fields III |
22.11.2016 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie - Verteidigung Masterarbeit Sebastian Manecke, TU Dresden Neue Sätze vom Eberhard-Typ |
13.12.2016 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dr. Karen Strung, Warsaw, Poland Group actions on Smale spaces and their associated C*-algebras |
12.04.2016 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. François Le Maître Université catholique de Louvain, Belgium Profinite branch groups and automatic continuity |
12.04.2016 (Di) 16:40 Uhr WIL A 124 |
Seminar Geometrie Kristian Knudsen Olesen University of Copenhagen, Denmark The Thompson groups T and V are not inner amenable |
14.04.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Miklós Abért MTA Alfréd Rényi Institute of Mathematics, Budapest, Hungary Entropy and graph convergence |
19.04.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Vadim Alekseev TU Dresden Dynamical Systems and Entropy I |
21.04.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Johann Thapper Université Paris-Est, France Fractional polymorphisms and LP relaxations of VCSPs |
26.04.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Vadim Alekseev TU Dresden Dynamical Systems and Entropy II |
28.04.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Benedikt Stufler Mathematisches Institut der LMU München, Germany Limits of random tree-like combinatorial structures |
03.05.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Vadim Alekseev TU Dresden Dynamical Systems and Entropy III |
10.05.2016 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Søren Knudby WWU Münster, Germany The Fourier and Rajchman algebras of a locally compact group |
12.05.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Alessandro Carderi TU Dresden, Institut für Geometrie An exotic group as limit of finite special linear groups |
20.05.2016 (Fr) ab 16 Uhr Dülfer-Saal, Alte Mensa |
Gauss-Vorlesung Prof. Dr. Nicolas Monod EPF Lausanne, Switzerland 100 Jahre Zweisamkeit - The Banach–Tarski paradox |
30.05.2016 (Mo) 11:10 Uhr WIL B 321 |
Graduate Lectures in Mathematics Jun Masamune Tohoku University, Japan Existence of non-constant integrable harmonic functions on Riemannian manifolds (1/3) |
31.05.2016 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Malte Gerold Ernst-Moritz-Arndt Universität Greifswald, Germany Subproduct systems and coalgebras |
02.06.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Tamás WaldhauserBolyai Institute, Szeged, Hungary Polycyclic monoids and Cuntz algebras via strange number systems |
06.06.2016 (Mo) 11:10 Uhr WIL C 129 |
Graduate Lectures in Mathematics Jun Masamune Tohoku University, Japan Existence of non-constant integrable harmonic functions on Riemannian manifolds (2/3) |
07.06.2016 (Di) 13:00 Uhr HSZ 403 |
Graduate Lectures in Mathematics Jun Masamune Tohoku University, Japan Existence of non-constant integrable harmonic functions on Riemannian manifolds (3/3) |
09.06.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Martin Finn-Sell University of Vienna, Austria Semigroups in coarse geometry and operator algebras |
13.06.2016 (Mo) 13:00 Uhr tba. |
Seminar Geometrie Rahel Brugger Universität Göttingen Property (T) for von Neumann algebras of discrete measurable groupoids |
14.06.2016 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Felix Pogorzelski Technion Haifa, Israel On non-commutative quasicrystals |
16.06.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Henry Bradford Universität Göttingen, Germany Expansion, Random Walks and Sieving in SL_{2}(F_{p} [t]) |
21.06.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Prof. Dr. Gerard Buskes University of Mississippi Big effects from small spaces, Lecture I |
23.06.2016 (Do) 14:50 Uhr WIL C 129 |
Graduate Lectures Prof. Dr. Gerard Buskes University of Mississippi Vector lattices: real and complex, Lecture II |
28.06.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Prof. Dr. Gerard Buskes University of Mississippi Lattice ordered algebras, Lecture III |
12.07.2016 (Di), |
Seminar Geometrie Jeremias Epperlein TU Dresden Topological conjugacies between cellular automata |
14.10.2014 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Prof. Dr. Emil Molnar Technische Universität Budapest Classical ball packing problems in the Thurston geometries |
16.10.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Manuel Bordirsky TU Dresden Ramsey Theory and Topological Dynamics |
23.10.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Andreas Thom TU Dresden Sofic Groups and Applications |
30.10.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Wieslav Kubis Universität Prag Banach-Mazur games on categories |
04.11.2014 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dipl.-Math. Tom Drescher TU Dresden Freie Spektraeder |
06.11.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. habil Tim Netzer TU Dresden Convex sets with semi-definite representations |
11.11.2014 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Nikolay Ivankov Universität Göttingen/z.Z. Gast der Universität Münster Towards KK-theory for ultrametric Banach algebras |
13.11.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. John Wilson University Oxford/Universität Leipzig Metric ultraproducts of finite simple groups |
18.11.2014 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Antoine Gournay TU Dresden The Liouville Property via Hilbertian Compression I |
20.11.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Jan-Christoph Schlage-Puchta Universität Rostock The Product Replacement Algorithm on the Symmetric Group |
25.11.2014 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Antoine Gournay TU Dresden The Liouville Property via Hilbertian Compression II |
04.-05.12.2014 (Do-Fr) | Geometrietag |
09.12.2014 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie (Diplomverteidigung) cand. math. Patrick Oberthür TU Dresden Algorithmische Ermittlung metrischer Daten von baumartigen Strukturen aus stereoskopischen Bildern und ihre Anwendung |
11.12.2014 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Isolde Adler Goethe Universität Frankfurt PAC learning of FO definable concepts & nowhere dense graph classes |
16.12.2014 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Prof. Dr. Peter Hornung TU Dresden Geometry of thin elastic films |
06.01.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dr. Nadine Große TU Dresden What is spin? |
08.01.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Jan Hladky Czech Academy of Sciences, Prague The Loebl-Komlos-Sos conjecture |
13.01.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Prof. Dr. Ulrich Brehm TU Dresden Compact Nil-manifolds |
15.01.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Marcello Mamino LIX Paris Groups definable in two orthogonal sorts |
20.01.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dr. Undine Leopold TU Chemnitz Vertex-Transitive Polyhedra of Higher Genus |
29.01.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Anton Klyachko Lomonossov-Universität Moskau Surprising divisibilities in group theory |
05.02.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik JProf. Dr. Martin Schneider TU Dresden Invariants of group actions and their connection to amenability |
19.02.2015 (Do) 13:00 Uhr WIL A 120 |
Graduate Lectures: A crash course on K-theory Prof. Guillermo Cortinas Universidad de Buenos Aires Middle algebraic and topological K-theory: K_0 and K_1 |
26.02.2015 (Do) 13:00 Uhr WIL A 120 |
Graduate Lectures: A crash course on K-theory Prof. Guillermo Cortinas Universidad de Buenos Aires Higher and lower K-theory: the excision problem |
05.03.2015 (Do) 13:00 Uhr WIL A 120 |
Graduate Lectures: A crash course on K-theory Prof. Guillermo Cortinas Universidad de Buenos Aires Comparing K-theories |
14.04.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie cand.math. Almuth Sürmann TU Dresden Diplomverteidigung |
23.04.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Andreas Thom TU Dresden Group laws for finite simple groups |
28.04.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dipl.-Math. Christian Oertel TU Dresden Dynamische Eigenschaften von Quasikristallen |
30.04.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik |
07.05.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Viola Meszaros TU Berlin Voronoi game on graphs |
12.05.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dr. Tobias Oertel-Jäger TU Dresden Amorphic complexity of Toeplitz flows and quasicrystals |
19.05.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dipl.-Math. Andreas Kübel Uni Leipzig Equivariant Differential Cohomology |
21.05.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Alessandro Carderi ENS Lyon Space of actions, ultraproducts and sofic entropy |
09.06.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie M.Sc. Sandra Lang TU Darmstadt Approximation of Projective Tensor Norms with Convex Algebraic Geometry |
11.06.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Anusch Taraz TU Hamburg-Harburg Embedding and packing large graphs into dense and sparse graphs |
07.07.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Dr. Nhân Phú Chung Vietnam National University at Ho-Chi-Minh-City Entropy theory of sofic groups |
16.07.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Phillip Wesolek UC Louvain Elementary amenable groups and the space of marked groups |
21.07.2015 (Di) 15:00 Uhr WIL A 120 |
Seminar Geometrie Pierre-Nicolas Jolissaint Université de Neuchâtel Embeddings of Groups into Hilbert spaces: Motivations and Examples |
30.-31.07.2015 (Do-Fr) | Conference Groups and Topological Groups |
15.10.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Agelos Georgakopoulos University Warwick Group Walk Random Graphs |
20.10.2015 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Antoine Gournay TU Dresden Random walks on groups I |
27.10.2015 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Prof. Dr. Andreas Thom TU Dresden Danzer's problem and topological dynamics |
29.10.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Damian Osajda Uniwersytet Wrocławski and IMPAN Embedding expanders in groups and applications |
03.11.2015 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Antoine Gournay TU Dresden Random walks on groups II |
05.11.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Hanno Lefmann TU Chemnitz Infinite partition regular linear systems of equations |
06.11.2015 (Fr) 11:10 Uhr WIL C 206 |
Seminar Geometrie Prof. Dr. Brita Nucinkis Royal Holloway London Quasi-automorphisms of trees |
10.11.2015 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures Dr. Antoine Gournay TU Dresden Random walks on groups III |
17.11.2015 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Jasmin Matz Universität Leipzig Distribution of Hecke eigenvalues for GL(n) |
19.11.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Andreas Thom TU Dresden Quasi-isometry and topological orbit equivalence |
24.11.2015 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures PD Dr. Tim Netzer TU Dresden Positive polynomials and optimization I |
26.11.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Sean Eberhard, MMath (Cantab) Oxford University Invariable generation of the symmetric group |
01.12.2015 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures PD Dr. Tim Netzer TU Dresden Positive polynomials and optimization II |
03.12.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Katrin Tent Universität Münster Kurze Beschreibungen endlicher Gruppen (mit A. Nies) |
08.12.2015 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures PD Dr. Tim Netzer TU Dresden Positive polynomials and optimization III |
10.12.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Michael Pinsker Czech Academy of Sciences, Prague Uniform Birkhoff |
15.12.2015 (Di) 14:50 Uhr WIL A 120 |
Seminar Geometrie Dr. Vadim Alekseev TU Dresden/Universität Göttingen Gromov's polynomial growth theorem |
17.12.2015 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Jérémie Brieussel Université de Montpellier Speed of random walks, isoperimetry and compression on finitely generated groups |
07.01.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Dr. Marcello Mamino TU Dresden tba |
12.01.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures JProf. Martin Schneider TU Dresden Rosenthal's l^{1}-Theorem I |
19.01.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures JProf. Martin Schneider TU Dresden Rosenthal's l^{1}-Theorem II |
21.01.2016 (Do) 13:15 Uhr WIL C 133 |
Seminar Algebra, Geometrie und Kombinatorik Prof. Dr. Manuel Bodirsky TU Dresden Tree-like homogeneous structures, their reducts, automorphism groups, and polymorphism clones |
26.01.2016 (Di) 14:50 Uhr WIL A 120 |
Graduate Lectures JProf. Martin Schneider TU Dresden Rosenthal's l^{1}-Theorem III |
09.02.2016 (Di) 14:50 Uhr WIL A 120 |
Diplomverteidigung Hella Epperlein TU Dresden Kompatible Triangulierungen einfacher ebener Polygone |