bio  website  regularize.wordpress.com 

location  Braunschweig, Germany  
age  36  
visits  member for  4 years, 2 months 
seen  15 hours ago  
stats  profile views  1,784 
Professor at TU Braunschweig.
Area: Inverse problems, regularization theory, applied functional analysis, mathematical image processing.
1d

comment 
Open problems in compressed sensing
One thing is that it makes a huge difference if one answers this question as a mathematician or as an engineer. Well, of course this is site for mathematics but the idea of compressed sensing is really a practical one: get information about a high dimensional object that lives in lower dimensional but nonlinear subspace from few measurements. The meaning of all ingredients is debatable here and varies a lot from problem to problem. Hence one open problem is to find the right mathematical formulation of the problem... 
Dec 19 
comment 
Image of (right) inverse trace map $\xi\colon H^{\frac 12}(\partial\Omega) \to H^1(\Omega)$ dense in $H^1(\Omega)$?
Ok, right  I thought that I had a basic misconception about the problem… 
Dec 19 
comment 
journal to submit mathematic books' review
The German "Mathematische Semesterberichte" publishes such reviews (probably only in German). 
Dec 19 
reviewed  Close How to construct a graph with arbitrarily large girth and large chromatic number? 
Dec 19 
reviewed  Leave Open Image of (right) inverse trace map $\xi\colon H^{\frac 12}(\partial\Omega) \to H^1(\Omega)$ dense in $H^1(\Omega)$? 
Dec 19 
comment 
Image of (right) inverse trace map $\xi\colon H^{\frac 12}(\partial\Omega) \to H^1(\Omega)$ dense in $H^1(\Omega)$?
Isn't solving the respective Dirichlet problem saying that the image contains $H^{3/2}$? 
Dec 16 
reviewed  Close Derangement,recursion and circular permutation 
Dec 16 
reviewed  Close Alexander duality theorem 
Dec 11 
revised 
What is an extragradient method?
corrected spelling 
Dec 10 
answered  Galerkin Projection on Integral Operators 
Dec 10 
answered  What is an extragradient method? 
Dec 7 
comment 
Banach space of discontinuous functions(Killing continuous functions)
"Appropriate quotient space" Do you have an idea how this space looks like (or how the space which you divide by)? I guess the quotient contains all characteristic functions of all points and then it wouldn't be separable in the first norm. The second norm looks pretty weired to me… 
Dec 4 
comment 
$Ax=b$ in a function space
I am not sure what you are after. Do you want to show that the solution depends continuously on the matrix? Are you especially interested in the case where $A$ gets singular? 
Nov 27 
awarded  Notable Question 
Nov 25 
accepted  Geometric measures different from Hausdorff 
Nov 25 
comment 
Continuous versions of tensors/ Tensors with infinite indices?
A situation where this works pretty straightforward is the case of functionals on $L^2$ (also on $L^p$ with $1<p<\infty$). There, the functionals are identified with functions, e.g. $(L^2)'=L^2$ and the tensor product of $L^2$ with itself is simple enough (en.wikipedia.org/wiki/Tensor_product_of_Hilbert_spaces). 
Nov 25 
comment 
Reference for a strong intermediate value theorem for measures
Actually, your statement is not strictly stronger than the result the OP is asking for since he wants the sets $S_t$ to be nested. 
Nov 20 
reviewed  Leave Open “Almost” zeta function 
Nov 19 
comment 
Removing constraints in convex optimization
Well, ehm, actually I don't see it either… Adapted my answer which is only a "partial answer" now… 
Nov 19 
revised 
Removing constraints in convex optimization
Extended and corrected 