News
News
First talk in the Graduate Student Speaker Series in the WT 2025/26
Nils Kober will give a talk in the Graduate Student Speaker Series with the title "Transfer learning for maximum likelihood estimation" on Wednesday, November 12, 2025, at 14:15 in SR 127/128, Ernst-Zermelo-Str. 1.
Nikolausvorlesung: Von Euklid zu Escher
Am 5.12.2025, 18.00 im HS II trägt Wolfgang Soergel vor. Anschließend gibt es ein Get-together und Glühwein.
Vorträge der nächsten sieben Tage
Bernd Rummler: (Magdeburg)
Remarks to exact Poincaré Constants in n-dimensional Annuli and Balls
Dienstag, 11.11.25, 14:15-15:15, Seminarraum 226, HH10
Abstract: We study n-dimensional annuli and n-dimensional balls, where we suppose n ∈ {2,..,N} with N < ∞.
We investigate in our non-dimensional setting each annulus ΩA- defined via two concentrical balls with
radii A/2 and A/2 + 1 in Rn - and n-dimensional open unit balls as ”limits” of ΩAfor A → 0. We provide
calculated (precise) Poincar´ e constants for scalar functions (with vanishing Dirichlet traces on the boundary)
in dependence of the inner diameter A and the dimension nof the space Rn for these geometries. Addi-
tionally we lay open the direct match of the Poincar´ e constants for solenoidal vector fields and the Poincaré
constants for scalar functions (both with vanishing Dirichlet traces on the boundary) for solenoidal vector
in space R2 resp. R3 with the Poincar´ e constants for scalar functions in R4 resp. R5. Generally we use the
first eigenvalues of the scalar Laplacian (or the first eigenvalues the Stokes operator) for the calculation of
the Poincar´ e constants. Supplementary, corresponding problems in domains Ω∗
σ (cf. e.g. the 3d-annuli from
[12]) are investigated - for comparison but also to provide the limits for A → 0. These domains Ω∗
σ enable
us to use the Green’s function of the Laplacian on Ω∗
σ with vanishing Dirichlet traces on ∂Ω∗
σ to show that
for σ → 0 the first eigenvalue here tends to the first eigenvalue of the corresponding problem on the open
unit ball in Rn . On the other hand, we take advantage of the so-called small-gap limit for A → ∞ like in
our papers to Poincar´ e constants in annuli (cf. [10] and [11]).
Yuchen Bi: (Universität Freiburg)
Stability of the Clifford Torus as a Willmore Minimizer
Dienstag, 11.11.25, 16:15-17:45, Seminarraum 125
Abstract: This is joint work with Jie Zhou (Capital Normal University). We prove that surfaces in $\mathbb{S}^3$ with genus $\geq 1$ and Willmore energy $\leq 2\pi^2 + \delta^2$ are quantitatively close to the Clifford torus after a conformal transformation. The closeness is measured in three aspects: $W^{2,2}$ parametrization, $L^\infty$ conformal factor, and conformal structure, with linear dependence on $\delta$.
Nils Kober: (Freiburg)
Transfer learning for maximum likelihood estimation
Mittwoch, 12.11.25, 14:15-15:45, SR 127/128