Upcoming Events
- Monday, 10.03.2025, 13:30 (WIAS-405-406)
- Berlin Oberseminar: Optimization, Control and Inverse Problems
Dr. Marius Zeinhofer, ETH Zürich, Switzerland:
First Optimize, Then Discretize for Scientific Machine Learning
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
This talk provides an infinite-dimensional viewpoint on optimization problems encountered in scientific machine learning and discusses the paradigm first optimize, then discretize for their solution. This amounts to first choosing an appropriate infinite-dimensional algorithm which is subsequently discretized in the tangent space of the neural network ansatz. To illustrate this point, we show that recently proposed state-of-the-art algorithms for scientific machine learning applications can be derived within this framework. Finally, we discuss the crucial aspect of scalability of the resulting algorithms.
Further Informations
Berlin Oberseminar: Optimization, Control and Inverse Problems
Host
WIAS Berlin
- Tuesday, 11.03.2025, 14:00 (WIAS-Library)
- Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations / Mathematical Optimization
Dr. Marcelo Bongarti, WIAS Berlin:
Multi-objective optimization with linear hyperbolic PDE constraints: generalized Nash equilibrium problems and gas market applications
more ... Location
Weierstraß-Institut, Hausvogteiplatz 5-7, 10117 Berlin, R411
Abstract
The concept of Nash equilibrium is fundamental to a wide range of applications, spanning fields from particle mechanics to micro and macroeconomics. However, much of the existing literature focuses on finite-dimensional settings. In this seminar, we draw on energy markets coupled with transport dynamics to motivate the study of multi-objective optimization problems with hyperbolic PDE constraints. We will explore the core ideas and challenges posed by generalized Nash equilibrium problems, particularly those related to dimensionality and regularity. Finally, we present some recent results on the existence and characterization of equilibria, emphasizing optimality conditions as a framework for understanding such solutions.
Further Informations
Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations
Host
WIAS Berlin
- Thursday, 13.03.2025, 10:00 (WIAS-405-406)
- Software and Data Seminar
Dr. Jan Philipp Thiele, WIAS Berlin:
Introduction to test driven development
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Software and Data Seminar
Host
WIAS Berlin
- Thursday, 13.03.2025, 14:00 (WIAS-405-406)
- Seminar Numerische Mathematik
Dr. John Papadopoulos, WIAS Berlin:
Hierarchical proximal Galerkin: a fast hp-FEM solver for variational problems with pointwise inequality constraints
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Further Informations
Numerical mathematics seminars
Host
WIAS Berlin
- Wednesday, 19.03.2025, 11:30 (WIAS-405-406)
- Seminar Interacting Random Systems
César Zarco-Romero:
The stacks picture of a uniform spanning tree
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
In contrast to Wilson's algorithm, the Stacks picture is a less known notion for efficiently generating a spanning tree at random in a connected graph. We revisit both tools related to loop-erased random walks. For ease of presentation, we restrict our attention to two dimensions for the infinite case. We will also mention a couple of points of intersection in other areas in Probability where research is being developed.
Host
WIAS Berlin
- March 26 – 28, 2025 (IOW)
- Workshop/Konferenz: Leibniz MMS Days 2025
more ... Location
Leibniz Institute for Baltic Sea Research Warnemünde (IOW).
Host
Leibniz Institute for Baltic Sea Research Warnemünde (IOW)
WIAS Berlin
- Thursday, 27.03.2025, 14:00 (WIAS-405-406)
- Seminar Numerische Mathematik
Prof. Cornelis Vuik, Delft University of Technology:
Resolving divergence: the first multigrid scheme for the highly indefinite Helmholtz equation using classical components
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406
Abstract
In this talk, we (V. Dwarka and C. Vuik) present the first stand-alone classical multigrid solver for the highly in- definite 2D Helmholtz equation with constant costs per iteration, addressing a longstanding open problem in numerical analysis [1]. Our work covers both large constant and non- constant wavenumbers up to k = 500 in 2D. We obtain a full V - and W -cycle without any level-dependent restrictions. Another powerful feature is that it can be combined with the computationally cheap weighted Jacobi smoother. The key novelty lies in the use of higher-order inter-grid transfer operators [2]. When combined with coarsening on the Complex Shifted Laplacian, rather than the original Helmholtz operator, our solver is h-independent and scales linearly with the wavenumber k. If we use GMRES(3) smoothing we obtain k- independent convergence, and can coarsen on the original Helmholtz operator, as long as the higher-order transfer operators are used. This work opens doors to study robustness of contemporary solvers, such as machine learning solvers inspired by multigrid components, without adding to the black-box complexity.
Host
WIAS Berlin