Upcoming Events
- Wednesday, 08.05.2024, 11:30 (WIAS-405-406)
- Seminar Interacting Random Systems
Tejas Iyer, WIAS Berlin:
Persistent hubs in generalised preferential attachment trees and certain branching processes
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
In a tree growing in discrete time-steps, a node is called a persistent hub if it becomes, and remains, the fixed node of maximal degree during the evolution of the process. For a large class of generalised preferential attachment trees, we provide necessary and sufficient criteria for the emergence of a persistent hub, building on previous work by Dereich and Mörters; Galashin, and Banerjee and Bhamidi. During the talk, we will explore part of the proof, delving into the connection with continuous time branching processes.
Further Informations
Seminar Interacting Random Systems (Hybrid Event)
Host
WIAS Berlin
- Wednesday, 08.05.2024, 14:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Markus Schmidtchen, Technische Universität Dresden:
Gradient flow solutions for porous medium equations with nonlocal Lévy-type pressure
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
We study a porous medium-type equation whose pressure is given by a nonlocal Lévy-operator associated to a symmetric jump Lévy kernel. The class of nonlocal operators under consideration appears as a generalisation of the classical fractional Laplace operator. For the a class of Lévy-operators, we construct weak solutions using minimising movements. (Joint work with G. Foghem and D. Padilla.)
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Tuesday, 14.05.2024, 15:00 (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. Thomas Möllenhoff, RIKEN Center for Advanced Intelligence Project, Japan:
Variational learning for large deep networks
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
We present extensive evidence against the common belief that variational Bayesian learning is ineffective for large neural networks. First, we show that a popular deep learning method called sharpness-aware minimization (SAM) solves an optimal relaxation of the variational Bayesian objective. Then, we demonstrate that a direct optimization of the variational objective with an Improved Variational Online Newton method (IVON) can consistently match or outperforms Adam for training large networks such as GPT-2 and ResNets from scratch. IVON's computational costs are nearly identical to Adam but its predictive uncertainty is better. We show several new use cases of variational learning where we improve fine-tuning and model merging in Large Language Models, accurately predict generalization error, and faithfully estimate sensitivity to data. We find overwhelming evidence in support of effectiveness of variational methods for deep learning.
Further Informations
Hybrid event. Dieser Vortrag findet auch via Zoom statt: https://zoom.us/j/492088715
Host
WIAS Berlin
- Wednesday, 15.05.2024, 14:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Erica Ipocoana, Freie Universität Berlin:
Non-isothermal phase-field models for tumor growth
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
We present two different diffuse interface models for tumor growth. In this context, the tumor is seen as an expanding mass surrounded by healthy tissues, while the interface in between contains a mixture of both healthy and tumor cells. The evolution of the system is assumed to be governed by biological mechanisms such as proliferation of cells via nutrient consumption and apoptosis. Besides, both the models include the effects of temperature variations. From the medical point of view, it is clear that the temperature does have effects on tumor growth and that in particular hyperthermia can lead to partial or complete destruction of tumor cells. The first model is a Cahn--Hilliard model, while the second is of Allen--Cahn type. After deriving the models following the microforces approach, we focus on proving the well-posedness and compare which regularity we are able to get for the solutions. Part of these results have been obtained in a recent collaboration with Stefania Gatti and Alain Miranville.
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- May 21 – 24, 2024 (ZIB-SEM)
- Workshop/Konferenz: QUANTUM OPTIMAL CONTROL From Mathematical Foundations to Quantum Technologies
more ... Location
Zuse-Zentrum für Informationstechnik (ZIB), Takustr. 7, 14195 Berlin, Seminarraum
Abstract
This workshop is part of the Thematic Einstein Semester “Mathematics for Quantum Technologies” (Summer 2024) funded by the Cluster of Excellence MATH+ and the Einstein Foundation Berlin. A central objective of the workshop is to promote an exchange between mathematicians, physicists and engineers across disciplines on the subject of optimal control of quantum systems.
Host
Freie Universität Berlin
WIAS Berlin
Technische Universität Berlin
Zuse Institute Berlin
- Wednesday, 22.05.2024, 14:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Jürgen Sprekels, WIAS Berlin:
Necessary and sufficient optimality conditions in the sparse optimal control of singular Allen--Cahn systems with dynamic boundary conditions
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Further Informations
Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Wednesday, 05.06.2024, 11:30 (WIAS-405-406)
- Seminar Interacting Random Systems
Gerónimo Uribe Bravo, Universidad Nacional Autónoma de México, Mexiko:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Seminar Interacting Random Systems (Hybrid Event)
Host
WIAS Berlin
- July 1, 2024 (WIAS-ESH)
- Workshop/Konferenz: Developments in Computational Finance - Honoring John Schoenmakers on the occasion of his retirement
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Host
WIAS Berlin
- Wednesday, 10.07.2024, 14:15 (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Caroline Lasser, Technische Universität München:
Variational Gaussian approximation for quantum dynamics
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
The talk considers the time-dependent Schrödinger equation with smooth magnetic and electric potentials in semiclassical scaling. We analyse nonlinearly parametrized approximations by single Gaussian wave packets via the Dirac--Frenkel variational principle. We derive ordinary differential equations of motion for the parameters of the variational solution. We present L2-error bounds and unexpectedly accurate observable error bounds. This is joint work with S. Burkhard, B. Dörich, and M. Hochbruck.
Host
Humboldt-Universität zu Berlin
WIAS Berlin
- Monday, 15.07.2024, 10:00 (WIAS-ESH)
- MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
First advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
Topic: Setting the scene
Quantization of the electromagnetic field in media and in space-time
Normal modes and harmomic oscillators
Zero-point energy
Casimir's cavity: 1D case, zeta-function renormalization
Casimir's cavity: 3D case, Casimir's renormalization
Host
WIAS Berlin
Einstein Foundation Berlin
- Tuesday, 16.07.2024, 10:00 (WIAS-ESH)
- MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
Second advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
Topic: Lifshitz theory
The need for a theory in dispersive and dissipative media
Point-splitting method
Fluctuation-dissipation theorem
Kubo-Martin-Schwinger relation
Lifshitz formula in planar, piece-wise homogenous media
Host
WIAS Berlin
Einstein Foundation Berlin
- Thursday, 18.07.2024, 10:00 (WIAS-ESH)
- MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
Third advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
Topic: Applications
Imaginary frequencies for capturing the broad band of quantum forces
Thermal Casimir effect
Perfectly conducting cavity
Magnetic mirror and Casimir repulsion
Permittivity hierarchy and repulsive Casimir forces
Negative refraction and quantum levitation
Engineering in the imaginary part of the spectrum
Host
WIAS Berlin
Einstein Foundation Berlin
- Friday, 19.07.2024, 10:00 (WIAS-ESH)
- MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
Fourth advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstract
Topic: Outlook
The quantum vacuum seen by accelerated observers (relativistic acceleration, Rindler coordinates, Unruh effect)
Entanglement in the quantum vacuum
Classical analogue of the Unruh effect
The case for a Casimir cosmology
Host
WIAS Berlin
Einstein Foundation Berlin
