3,538 reputation
1851
bio website regularize.wordpress.com
location Braunschweig, Germany
age 36
visits member for 4 years, 8 months
seen 4 hours ago

Professor at TU Braunschweig.

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


May
22
reviewed Close Searching for $C^*$
May
22
reviewed Close Maximum entropy to fit Johnson distribution by moments
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."
May
13
answered Rate of convergence for cyclic gradient descent
May
12
awarded  Necromancer
May
12
reviewed Close Can the image of a disk have nontrivial Hausdorff measure for $1 < d < 2$?
May
6
answered Examples of common false beliefs in mathematics
Apr
24
reviewed Approve Embedding Theorem for topological spaces, and in general
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
21
reviewed Reopen Decomposition space of $\mathbb{C}$ by concentric circles
Apr
20
awarded  Good Answer
Apr
14
revised Is there a classification of 2d extended TQFTs with defects?
spelled out TQFT and added link
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.
Apr
7
awarded  Necromancer
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?