Sprungmarken

Servicenavigation

TU Dortmund

Hauptnavigation


Bereichsnavigation

Mathematisches Kolloquium

Datum Gastredner Thema Ort
Im Rahmen des Mathematischen Kolloquiums
Im Rahmen des Oberseminars Stochastik und Analysis
Oberseminar Analysis, Mathematische Physik, Dynamische Systeme
27.04.2017
16.15
Sjoerd Dirksen
RWTH Aachen
Sparse recovery with heavy-tailed random matrices

Zusammenfassung


In compressed sensing and high-dimensional statistics, one is faced with the problem of reconstructing a high-dimensional vector x from underdetermined, possibly noisy linear measurements y=Ax. Research from the last decade has shown that this can be done in a computationally efficient way if one knows that the target vector x is sparse or, more generally, comes from a ``low-complexity`` model. The best known reconstruction results are known for ?well-behaved? random measurement matrices, e.g., Gaussian matrices. In this talk I will consider the problem of recovering x via a convex program, called \ell_p-constrained basis pursuit, in the scenario that A contains heavy-tailed random variables. I will present recent work that shows that under surprisingly light conditions on the distribution on the entries, one can reconstruct x from an optimal number of measurements. If time permits, I will show an application to reconstruction from quantized heavy-tailed measurements. I will not assume any prior knowledge of compressed sensing during the presentation. Based on joint work with Guillaume Lecué (Ecole Polytechnique) and Holger Rauhut (RWTH Aachen University).
[Abstract]
[WWW]
Vortrag am Donnerstag dem 27. April 2017 um 16.15 im Seminarraum M/611.
M/611
Vortrag im GRK 2131
Im Rahmen des Mathematischen Kolloquiums
Im Rahmen des Oberseminars Stochastik und Analysis
15.05.2017
17 Uhr
Prof. Dr. Wolfgang König
TU Berlin / WIAS
The principal part of the spectrum of a random Schrödinger operator in a large box
Vortrag im Rahmen des Graduiertenkollegs 2131 'Phänomene hoher Dimensionen in der Stochastik - Fluktuationen und Diskontinuität'
Mathematikgebäude, Hörsaal E28
Vortrag im GRK 2131
Im Rahmen des Mathematischen Kolloquiums
Im Rahmen des Oberseminars Stochastik und Analysis
22.05.2017
17 Uhr
Prof. Dr. Karl-Theodor Sturm
Rheinische Friedrich-Wilhelms-Universität Bonn
Heat flow, optimal transport, and Ricci curvature on metric measure spaces
Vortrag im Rahmen des Graduiertenkollegs 2131 'Phänomene hoher Dimensionen in der Stochastik - Fluktuationen und Diskontinuität'
Mathematikgebäude, Hörsaal E28
Im Rahmen des Mathematischen Kolloquiums
Oberseminar Analysis, Mathematische Physik, Dynamische Systeme
13.06.2017
14.15
Konstantin Pankrashkin
University Paris-Sud
Self-adjoint operators of the type div sgn grad

Zusammenfassung


Being motivated the study of negative-index metamaterials, we will discuss the definition and the spectral properties of the operators given by the differential expressions div h grad in a bounded domain U with a function h which is equal to 1 on a part of U and to a constant b<0 on the rest of U. We will see how the properties of such operators depend on the parameter b and on the geometry of U. In particular, one can have a non-empty essential spectrum. Based on a joint work with Claudio Cacciapuoti and Andrea Posilicano (University of Insubria).
[Abstract]
[WWW]
M E19