Veranstaltungen
- Montag, 22.04.2024, 13:30 Uhr (WIAS-ESH)
- Berlin Oberseminar: Optimization, Control and Inverse Problems
Dr. Johannes Royset, University of Souther California, USA:
Approximations of Rockafellians, Lagrangians, and Dual Functions. The case for solving surrogates instead of actual optimization problems
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
Optimization problems are notorious for being unstable in the sense that small changes in their parameters can cause large changes in solutions. However, Rockafellian relaxations, Lagrangian relaxations, and dual problems are typically more stable. While focusing on the nonconvex case, we develop sufficient conditions under which approximations of Rockafellian relaxations, Lagrangian relaxations, and dual problems convergence, epigraphically or hypographically, to limiting counterparts, and quantify the rate of convergence. The conditions are milder than those required by approximations of the actual problems confirming the importance of these surrogate problems. We illustrate the results in the context of composite problems, stochastic optimization, and Rockafellians constructed by augmentation.
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Berlin Oberseminar: Optimization, Control and Inverse Problems
Veranstalter
WIAS Berlin
- Dienstag, 23.04.2024, 15:00 Uhr (WIAS-405-406)
- Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Priv.-Doz. Dr. John Schoenmakers, WIAS Berlin:
Optimal stopping with randomly arriving opportunities to stop
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
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Hybrid event. Dieser Vortrag findet auch via Zoom statt: https://zoom.us/j/492088715
Veranstalter
WIAS Berlin
- Mittwoch, 24.04.2024, 11:30 Uhr (WIAS-405-406)
- Seminar Interacting Random Systems
Julia Hörmann, WIAS Berlin:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
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Seminar Interacting Random Systems (Hybrid Event)
Veranstalter
WIAS Berlin
- Mittwoch, 24.04.2024, 11:30 Uhr (WIAS-405-406)
- Seminar Interacting Random Systems
Julia Hörmann, WIAS Berlin:
High-dimensional random tessellations, deep neural networks and image classification in a security relevant setting
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstrakt
Random tessellations as hyperplane and Voronoi tessellations are probabilistic models studied in stochastic geometry. In the talk a line of research concerning asymptotic properties of random tessellations for growing dimension of the Euclidean space is presented. Random tessellations have applications in data science and multivariate statistics since each classification problem corresponds to the search for a tessellation. Here, in particular deep neural networks are a recent controversial approach with great successes in machine learning challenges on the one hand but the lack of mathematical understanding and robustness on the other hand. For illustration we present the results of a feasibility study concerning the application of deep neural networks in a security relevant setting. Improving the mathematical understanding of deep neural networks is thus a topic of high interest. The talk will be concluded with some open mathematical questions.
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Seminar Interacting Random Systems (Hybrid Event)
Veranstalter
WIAS Berlin
- Mittwoch, 24.04.2024, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Ruming Zhang, Technische Universität Berlin:
Direct and inverse problems in periodic waveguides
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
Waveguides play important roles in many application areas, for example, in communications. An essential topic in the development of modern techniques is based on the deep understanding of the behaviours of the waves propagating in the waveguides. Then, numerical methods are proposed to simulate the physical processes and mathematical methods are developed to solve the related inverse problems. In this talk, I will first focus on the direct problem, that is study the timeharmonic wave propagating in the periodic waveguide both analytically and numerically. The problem is modeled by the Helmholtz equation in a periodic strip. Afterwards, I will also introduce one example of the solution to an inverse problem.
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Oberseminar “Nichtlineare Partielle Differentialgleichungen” (Langenbach Seminar)
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- Dienstag, 30.04.2024, 10:15 Uhr (WIAS-406)
- Seminar Nichtlineare Optimierung und Inverse Probleme
Dr. Igor Voulis, Georg-August-Universität Göttingen:
An adaptive stochastic FEM method for the Poisson problem
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Veranstalter
WIAS Berlin
- Dienstag, 14.05.2024, 15:00 Uhr (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
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstrakt
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.
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Hybrid event. Dieser Vortrag findet auch via Zoom statt: https://zoom.us/j/492088715
Veranstalter
WIAS Berlin
- 21. – 24. Mai 2024 (ZIB-SEM)
- Workshop/Konferenz: QUANTUM OPTIMAL CONTROL From Mathematical Foundations to Quantum Technologies
mehr ... Veranstaltungsort
Zuse-Zentrum für Informationstechnik (ZIB), Takustr. 7, 14195 Berlin, Seminarraum
Abstrakt
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.
Veranstalter
Freie Universität Berlin
WIAS Berlin
Technische Universität Berlin
Zuse Institute Berlin
- Mittwoch, 22.05.2024, 14:15 Uhr (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
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
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Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- Mittwoch, 05.06.2024, 11:30 Uhr (WIAS-405-406)
- Seminar Interacting Random Systems
Gerónimo Uribe Bravo, Universidad Nacional Autónoma de México, Mexiko:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
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Seminar Interacting Random Systems (Hybrid Event)
Veranstalter
WIAS Berlin
- 1. Juli 2024 (WIAS-ESH)
- Workshop/Konferenz: Developments in Computational Finance - Honoring John Schoenmakers on the occasion of his retirement
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Veranstalter
WIAS Berlin
- Montag, 15.07.2024, 10:00 Uhr (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” .
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
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
Veranstalter
WIAS Berlin
Einstein Foundation Berlin
- Dienstag, 16.07.2024, 10:00 Uhr (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” .
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
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
Veranstalter
WIAS Berlin
Einstein Foundation Berlin
- Donnerstag, 18.07.2024, 10:00 Uhr (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” .
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
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
Veranstalter
WIAS Berlin
Einstein Foundation Berlin
- Freitag, 19.07.2024, 10:00 Uhr (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” .
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
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
Veranstalter
WIAS Berlin
Einstein Foundation Berlin