Monday,
20241021
16:15

Raum 404, ErnstZermeloStr. 1
Maximilian Stegemeyer:
The Frobenius relation in string topology
String topology is the study of algebraic operations on the homology of the free loop space of a closed manifold. Two prominent operations are the ChasSullivan product and the GoreskyHingston coproduct. It is an important question what structure these two operations form together. We show that under a transversality condition a Frobeniustype relation for the product and the coproduct holds. As an application this yields the behaviour of the coproduct on product manifolds. This talk is based on joint work with Nathalie Wahl. 
Monday,
20241028
16:15

Raum 404, ErnstZermeloStr. 1
Bernd Ammann (Regensburg):
Selfadjoint codimension 2 boundary conditions for Dirac operators
Joint work with Nadine Große.
Let $N$ be an oriented compact submanifold in an oriented complete Riemannian manifold $M$. We assume that $M\setminus N$ is spin and carries a unitary line bundle $L$. We study the associated twisted Dirac operator, a priori defined on smooth section with compact support in the interior of $M\setminus N$. We are interested in selfadjoint extensions of this operator.
If $N$ has codimension~$1$, then this is the wellstudied subject of classical
boundary values for Dirac operators. If $N$ has codimension at least $3$, or if $N$ has codimension $2$ and if $L$ has trivial monodromy around $N$, then we obtain a unique selfadjoint extension which coincides with the classical selfadjoint Dirac operator on $M$. The submanifold $N$ is thus ``invisible''.
The main topic of this talk is thus the case of codimension~$2$ with nontrivial monodromy. We will classify all selfadjoint extensions.
This work is motivated by work of Portman, Sok and Solovej, who treated the special case of $M=S^3$ with a link, a case important in mathematical physics.
We thank Boris Botvinnik and Nikolai Saveliev for stimulating discussions about this topic. 
Monday,
20241111
16:15

Raum 404, ErnstZermeloStr. 1
Charlotte Dietze (LMU):
Weyl formulae for some singular metrics with application to acoustic modes in gas giants
We prove eigenvalue asymptotics of the LaplaceBeltrami operator for certain singular Riemannian metrics. This is motivated by the study of propagation of soundwaves in gas planets. This is joint work with Yves Colin de Verdière, Maarten de Hoop and Emmanuel Trélat. 
Monday,
20241118
16:15

Raum 404, ErnstZermeloStr. 1
Zhen Gao (Universität Augsburg):
Symplectic topology and rectangular peg problem
The rectangular peg problem, an extension of the square peg problem which has a long history, is easy to outline but challenging to prove through elementary methods. I will report the recent progress on the existence and multiplicity results, utilizing advanced concepts from symplectic topology, e.g. Jholomorphic curves and Floer theory. 
Monday,
20241125
16:00

Raum 404, ErnstZermeloStr. 1
Misha Temkin:
TBA
TBA 
Monday,
20241202
16:15

Raum 404, ErnstZermeloStr. 1
Lukas Hoffmann:
TBA 
Thursday,
20241212
10:0012:00

Raum 414, ErnstZermeloStr. 1
Stephan Mescher (Uni Halle):
TBA 
Monday,
20241216
16:1517:45

Raum 404, ErnstZermeloStr. 1
Dr. Jan Steinebrunner (Cambridge):
t.b.a. 
Monday,
20250113
16:15

Raum 404, ErnstZermeloStr. 1
Nelia Charalambous (University of Cyprus):
TBA 
Monday,
20250127
16:1517:45

Raum 404, ErnstZermeloStr. 1
Urs Lang (ETHZ):
t.b.a. 