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Monday, 25 March
Time Speaker Title Location
13:15 - 14:15 Vladimir Dotsenko
Université de Strasbourg
Abstract
I shall recall the definition of a wheeled operad (introduced by Merkulov about 15 years ago) and explain how homotopy invariants of wheeled operads appear naturally when computing stable homology of Lie algebras of derivations of free algebras. This a common generalization of the Loday-Quillen-Tsygan theorem on additive K-theory of an associative algebra, and the Fuchs' stability theorem for homology of the Lie algebra of vector fields.
Talks in Mathematical Physics
Lie algebra homology and wheeled operads
HG G 43
15:15 - 16:30 Jean-Philippe Chassé
ETH Zürich
Abstract
There are many natural metrics that one can put on the collection of all exact (closed connected) Lagrangians of a given Liouville manifold: Lagrangian Hofer metric, spectral metric, shadow metric, etc. However, in most instances, the known properties of the ensuing metric space are quite limited, as these spaces tend to be quite unruly. For this reason, I have previously studied the subspace of Lagrangians respecting an appropriate notion of "geometric boundedness"—a much more manageable space as it turns out. In this talk, I will present some new results on the metric properties in this smaller space of geometrically bounded Lagrangians, where all these metrics behave essentially the same. As applications, we will get some yet-unknown topological properties of the space of all exact Lagrangians of a Liouville manifold.
Symplectic Geometry Seminar
The metric geometry of geometrically bounded Lagrangians
HG G 43
Tuesday, 26 March
Time Speaker Title Location
12:15 - 13:00 Daniel Gotsmann
ETH Zürich, Switzerland
Abstract
Spectroscopy historically and to this day has been an important part of night sky observation. In this talk we dive in to how spectroscopy works and what we can learn by analyzing a spectrum of a star. From the fundamentals of blackbody radiation to the stellar lifecycle an overview is given. Measurement results of different typed stars are presented and analyzed.

More information: https://zucmap.ethz.ch/
ZUCCMAP
Stellar Spectroscopy and Classifying Stars
HG G 5
15:15 - 16:15 Prof. Dr. Anuj Kumar
UC Berkeley
Abstract
We construct nonunique solutions of the transport equation in the class $L^\infty$ in time and $L^r$ in space for divergence free Sobolev vector fields $W^{1, p}$. We achieve this by introducing two novel ideas: (1) In the construction, we interweave the scaled copies of the vector field itself. (2) Asynchronous translation of cubes, which makes the construction heterogeneous in space. These new ideas allow us to prove nonuniqueness in the range of exponents beyond what is available using the method of convex integration and sharply matchwith the range of uniqueness of solutions from Bruè, Colombo, De Lellis ’21.
Analysis Seminar
Nonunique solutions of the transport equation for Sobolev vector fields
HG G 43
16:30 - 18:15 Isabelle Gallagher

Abstract
Abstract: The evolution of a gas can be described by different models depending on the scale of observation. A natural question, raised by Hilbert in his sixth problem, is whether these models provide consistent predictions. On the one hand Lanford showed in 1974 that the Boltzmann equation appears as a law of large numbers in the low density limit of a gas of hard spheres, at least for very short times. On the other hand, fluid mechanics equations such as the Navier-Stokes equations can be derived from the Boltzmann equation in the limit of when the mean free path tends to zero. Reconciling both approaches in order to derive fluid mechanics equations from Newton's laws for the system of particles is to this day an open question. In this talk we shall explain these different limiting procedures, their difficulties and some recent advances in Hilbert's program.
Zurich Colloquium in Mathematics
On the dynamics of dilute gases
KO2 F 150
Wednesday, 27 March
Time Speaker Title Location
13:30 - 14:30 Pedram Safaee
Universität Zürich
Abstract
We will introduce the concept of twisted Birkhoff sum and the twisted Cocycle. We give some motivations for studying this Cocycle and discuss the positivity of the top Lyapunov exponent. This is based on joint work with Hesam Rajabzadeh.
Ergodic theory and dynamical systems seminar
Nondegeneracy of the spectrum of the twisted Cocycle for interval exchange transformations
HG G 19.1
14:30 - 16:00 John Ery
Examinar: Prof. Dr. P. Cheridito
Abstract
Doctoral Exam
Actuarial Data Science: lnsights from Pricing, Capital Modeling and CAT Bonds
LFW B 3
Thursday, 28 March
Time Speaker Title Location
16:15 - 17:15 Blandine Galiay
ENS Paris Saclay
Abstract
A divisible convex set is a properly convexe open subset of the projective space admitting a cocompact action of a discrete subgroup of its automorphism group. The study of these geometric objects started in the 60s with the work of Benzecri and has seen significant developments since then. Many connections have been established with other research areas, ranging from geometric structures to dynamical systems, including geometric group theory and symmetric spaces. In this presentation, our goal is to introduce recent generalizations of the theory of divisible convex sets. To do so, we will first introduce the various objects and fundamental concepts of the theory.
Geometry Graduate Colloquium
The theory of divisible convex domains, and generalizations
HG G 19.2
16:15 - 18:00 Prof. Dr. Marcin Napiórkowski
University of Warsaw
Abstract
According to the Bogoliubov theory, the low energy behaviour of the Bose gas at zero temperature can be described by non-interacting bosonic quasiparticles called phonons. In my talk I will explain how the damping rate of phonons at low momenta, the so-called Beliaev damping, can be computed with simple arguments involving an effective Friedrichs model for phonons.
PDE and Mathematical Physics
Beliaev damping in Bose gas
Y27 H 46
16:30 - 18:00 Cole Jeznach
Examinar: Prof. Dr. S. Mayboroda
Abstract
Doctoral Exam
Quantitative rectifiability and harmonic measure for sets of high co-dimension
HG E 33.3
Friday, 29 March
— no events scheduled today —
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