3,533 reputation
1851
bio website regularize.wordpress.com
location Braunschweig, Germany
age 36
visits member for 4 years, 7 months
seen 5 hours ago

Professor at TU Braunschweig.

Area: Inverse problems, regularization theory, applied functional analysis, mathematical image processing.


May
20
comment Projecting a convex partition onto a convex set
Err, sorry - of course, nonempty $X$ it should be…
May
20
comment Projecting a convex partition onto a convex set
$X$ could be empty or have $n-1$ points... You need some more conditions.
May
19
comment Splines linearly independent
What do you mean by "its unique smooth extension"?
May
14
comment Which way for reading the proofs?
@fanzheng I heard a similar quote about a famous optimizer "I don't read papers, I write them."
Apr
23
comment l1 Quadratic Programming
Noting that the above problem has all these guys as variables: Isn't that in standard for already?
Apr
23
comment A question involving Mazur's Lemma
Well, the degenerate case $y_n = x_n$ does not work so some assumption on the convex combination is needed.
Apr
14
comment 2, 3, and 4 (a possible fixed point result ?)
As far as I understood, the BGK (Browder-Göhde/Göbel-Kirk) fixed point theorem states that every non-expansive self-mapping on a non-empty, closed and convex subset of a uniformly convex Banach space has a fixed point.
Mar
27
comment Hadamard / matrix product adjoint
Ok, I see now. I think a better fit for this question would be scicomp.stackexchange.com. Anyway: The adjoint is defined by $\langle A^* y,x\rangle = \langle y,Ax\rangle$. You do adjoints one by one from outside to inside.
Mar
26
comment Hadamard / matrix product adjoint
Sorry, but this does not make sense. What is the Hadamard product of the matrix S and the vector Fx?
Mar
26
comment Hadamard / matrix product adjoint
Err... So x is a matrix?
Mar
26
comment Hadamard / matrix product adjoint
I could not parse your definition of the operator A. If D and S are matrices, do you build the Hadamard product with the matrix of the Fourier transform?
Mar
26
comment Convergence in energy of bounded (semi)subharmonic functions
Sorry for the late reply: I guess the best thing would be to write an answer yourself so that this is kept for the records.
Mar
17
comment Fredholm integral with functions constrained to [0;1]
For some reason I confused $g$ and $f$. Of course $f$ should be the unknown… Corrected.
Mar
16
comment Fredholm integral with functions constrained to [0;1]
The most simple thing that comes to mind is the projected gradient method, see my update.
Feb
27
comment What is an extragradient method?
Well, this shows that the term "extragradient" is indeed used differently.
Feb
19
comment Different styles of writing/reading articles
@FedericoPoloni I agree. When I wrote the comment, this question was closed without an answer, so it was unclear if it would ever get any answers here…
Feb
19
comment Different styles of writing/reading articles
Probably this question will get answers over at academia.stackexchange.com
Feb
17
comment How to solve the following generalized quadratic programming problem
Well its still convex, albeit non-smooth. Looks like primal-dual methods, alternating direction method of multipliers or so could be applied…
Feb
2
comment optimization of inverse matrix with constraint on matrix elements
Have you tried to formulate the optimality system, e.g. by using this: en.wikipedia.org/wiki/…
Jan
27
comment Reference : Special case of Banach-valued function integration by parts
I would start looking in Zeidler's books on functional analysis but I don't have access right now.