Monday,
20160418
16:15

Raum 404, Eckerstr. 1
NN:
Programmdiskussion 
Monday,
20160425
16:15

Raum 404, Eckerstr. 1
Prof. Dr. Bernhard Hanke (Augsburg):
Γstructures and symmetric spaces
Γstructures are weak forms of multiplications on closed oriented manifolds.
As shown by Hopf the rational cohomology algebras of manifolds admitting
Γstructures are free over odd degree generators. We prove that this condition
is also sufficient for the existence of Γstructures on manifolds which are
nilpotent in the sense of homotopy theory. This includes homogeneous spaces
with connected isotropy groups.
Passing to a more geometric perspective we show that on compact oriented
Riemannian symmetric spaces with connected isotropy groups and free rational
cohomology algebras the canonical products given by geodesic symmetries define
Γstructures. This extends work of Albers, Frauenfelder and Solomon on
Γstructures on Lagrangian Grassmannians. 
Monday,
20160502
16:15

Raum 404, Eckerstr. 1
Fabian Lehmann:
t.b.a. 
Monday,
20160509
16:15

Raum 404, Eckerstr. 1
Anja Wittmann:
Adiabatic Limits of Eta Invariants
We will introduce eta invariants, which are spectral invariants of Dirac operators, and the notion of adiabatic limits. Then we present some known results by Bismut, Cheeger and Dai before we give a partial answer in a more general setting. 
Monday,
20160523
16:15

Raum 404, Eckerstr. 1
Niccolò Pederzani (Leipzig):
Surgery stability of the space of metrics with invertible Dirac operator 
Monday,
20160613
16:15

Raum 414, Eckerstr. 1
Christian Ketterer:
Ricci curvature of nonsymmetric diffusion operators 
Monday,
20160620
16:15

Raum 404, Eckerstr. 1
Lu Feng:
Integral curvature and area of domains in surfaces 
Monday,
20160627
16:15

Raum 404, Eckerstr. 1
Jørgen Lye:
Minimal Geodesics on a K3
I will give an introduction to my PhD thesis topic. My emphasis will be on explaining the problem by stating known resutls of interest to a broader audience of differential geometers. Most of the talk should be understandable without a detailed knowledge of K3 surfaces. 
Monday,
20160704
16:15

Raum 404, Eckerstr. 1
Jonathan Wöhrle (Freiburg):
Aufblasung affiner Varietäten 
Monday,
20160711
16:15

Raum 404, Eckerstr. 1
YiSheng Wang:
Higher homotopies
Starting with the relation of infinite loop spaces and generalized cohomology theories, we use some simple examples to illustrate some special homotopy invariant properties of infinite loop spaces. Then we go on and introduce various delooping machines. In the end of the talk, a description of infinite loop space by Gammaspace will be given. 
Monday,
20160718
16:1517:15

Raum 404, Eckerstr. 1
Ursula Ludwig:
A Local Index Formula for the Intersection Euler Characteristic of an Infinite Cone
Universität Duisburg Essen
The study of global analysis of spaces with (isolated) conelike singularities has started with work of Cheeger in the 80s and has seen a rich development since. One important result is the generalisation of the ChernGaussBonnet theorem for these spaces, which is due to Cheeger. It establishes a relation between the $L^2$Euler characteristic of the space, the integral over the Euler form and a local contribution $\gamma$ of the singularities. The ``Cheeger invariant'' $\gamma$ is a spectral invariant of the link manifold.
The aim of this talk is to establish a local index formula for the intersection Euler characteristic of a cone. This is done by studying local index techniques as well as the spectral properties of the model Witten Laplacian on the infinite cone. As a result we express the absolute and relative intersection Euler characteristic of the cone as a sum of two terms, one of which is Cheeger's invariant $\gamma$. 
Monday,
20160725
16:15

Raum 404, Eckerstr. 1
Jan Steinebrunner:
Smoothing theory
Since Milnor discovered exotic 7spheres in 1956, it is known that a
topological manifold can have several nondiffeomorphic smooth
structures. The aim of smoothing theory is to calculate the set S(X) of
smoothings of a given topological manifold X in terms of a homotopy
theoretical property:
S(X) turns out to be in bijection with the set of lifts of a certain
classifying map.
In my talk I will introduce all necessary concepts such as mircobundles
and piecewise linear manifolds and try to illustrate their properties.
Then the fundamental theorem will be stated and important parts of the
proof will be sketched. In the end I hope to give some practical
advices on how to calculate structure sets. 
Monday,
20160822
16:15

Raum 404, Eckerstr. 1
Umberto Hryniewicz:
Local Morse homology with finitecyclic symmetry
Morse theory is concerned with the relationships between the
structure of the critical set of a function and the topology of the
ambient space where the function is defined. The applications of Morse
theory are ubiquitous in mathematics, since objects of interest
(geodesics, minimal surfaces etc) are often critical points of a
functional (length, area etc). In this talk I will review basic
concepts in Morse theory, and will focus on Hamiltonian dynamics where
the applications emerge from the fact that periodic solutions of
Hamilton's equations are critical points of the action functional. I
will explain how to define a local Morse homology of the action
functional at an isolated periodic orbit which takes into account the
symmetries associated to timereparametrization, and serves a
welldefined alternative to local contact homology. Then I will
explain dynamical applications. This is joint work with Doris Hein
(Freiburg) and Leonardo Macarini (Rio de Janeiro). 
Wednesday,
20160928
13:4515:15

Raum 125, Eckerstr. 1
Dr. Indrava Roy (Chennai):
HigsonRoe exact sequence and secondary $\ell^2$invariants
In this talk we give an overview of the HigsonRoe exact sequence for
discrete groups, also known as the analytic surgery sequence, and explain its
relation with secondary invariants of type rho. Using the machinery of
equivariant Roealgebras we shall also outline a proof of some rigidity results
of $\ell^2$rhoinvariants, generalizing earlier work of Higson and Roe. This
is joint work with M.T. Benameur. 