4 citations · 9 across the 6 of their papers we have counts for
9 papers
Constructive subsampling of finite frames with applications in optimal function recovery
Felix Bartel, Martin Schäfer, Tino Ullrich
In this paper we present new constructive methods, random and deterministic, for the efficient subsampling of finite frames in . Based on a suitable random subsampling…
A new upper bound for sampling numbers
Nicolas Nagel, Martin Schäfer, Tino Ullrich
We provide a new upper bound for sampling numbers associated to the compact embedding of a separable reproducing kernel Hilbert space into the space of sq…
Hyperbolic wavelet analysis of classical isotropic and anisotropic Besov-Sobolev spaces
M. Schäfer, T. Ullrich, B. Vedel
In this paper we introduce new function spaces which we call anisotropic hyperbolic Besov and Triebel-Lizorkin spaces. Their definition is based on a hyperbolic Littlewood-Paley an…
The Role of -Scaling for Cartoon Approximation
Martin Schäfer
The class of cartoon-like functions, classicly defined as piecewise functions consisting of smooth regions separated by discontinuity curves, is a well-established mode…
Bendlets: A Second-Order Shearlet Transform with Bent Elements
Christian Lessig, Philipp Petersen, Martin Schäfer
We introduce bendlets, a shearlet-like system that is based on anisotropic scaling, translation, shearing, and bending of a compactly supported generator. With shearing being linea…
General coorbit space theory for quasi-Banach spaces and inhomogeneous function spaces with variable smoothness and integrability
Henning Kempka, Martin Schäfer, Tino Ullrich
In this paper we propose a general coorbit space theory suitable to define coorbits of quasi-Banach spaces using an abstract continuous frame, indexed by a locally compact Hausdorf…
Multivariate -molecules
Axel Flinth, Martin Schäfer
The suboptimal performance of wavelets with regard to the approximation of multivariate data gave rise to new representation systems, specifically designed for data with anisotropi…
-Molecules
Philipp Grohs, Sandra Keiper, Gitta Kutyniok +1
Within the area of applied harmonic analysis, various multiscale systems such as wavelets, ridgelets, curvelets, and shearlets have been introduced and successfully applied. The ke…
Cartoon Approximation with -Curvelets
Philipp Grohs, Sandra Keiper, Gitta Kutyniok +1
It is well-known that curvelets provide optimal approximations for so-called cartoon images which are defined as piecewise -functions, separated by a singularity curve.…