2,787 reputation
1144
bio website regularize.wordpress.com
location Braunschweig, Germany
age 35
visits member for 3 years, 9 months
seen 2 hours ago

Professor at TU Braunschweig.

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


1d
comment Is this graph of reciprocal power means always convex?
Ok, my believe is destroyed… Another interesting question could be. What are $n$ and $p$ such that the respective function has most negative value in its second derivative?
2d
comment Is this graph of reciprocal power means always convex?
Good! It still puzzles me, why the quantity is convex in almost every case. I would still believe if somebody told me that convexity is true for large $n$…
2d
comment Is this graph of reciprocal power means always convex?
Some tests with extreme cases seem to indicate that the answer may be negative. The small negative part of the second derivative of the function for $n=3$ and values $p = [0.25\ 0.25\ 0.5]$ (see here) does not look like a numerical artifact. Other values that give suspicious results are tuples with a small number of entries (but more that two) that are close to the uniform distribution.
2d
comment Di Perna-Lions theory for transport equation
This does not seem to be a well formed question. What kind of "notes" do you expect? Apparently there is a lecture with the same title than this question happening right now at UofT. Do you refer to notes of this course? Also: What kind of doubts do you have for what particular issue? Oh, and don't crosspost (at least not without mentioning it) math.stackexchange.com/questions/873437/…. Finally, just googling your title leads to some lecture notes which may answer your question.
Jul
18
revised Proof correctness problem
Spelled out the acronym CFSG (my google search yielded the correct hit on place five…)
Jul
16
comment Metrization of weak convergence of signed measures
Sorry for longer quietness, but may I ask what problems do arise with this metric if the measures are signed? I thought that the constraint $|f(\omega)|\leq 1$ would take care of these. In the metric we use differences of measures anyway so what goes in the norm is generall signed.
Jul
16
reviewed Approve suggested edit on Sum over growing Young tableaux
Jul
16
accepted Is the prox-residual monotone?
Jul
16
comment Is the prox-residual monotone?
Great, thanks! Somehow, my examples where either somehow isotropic or random and did not show this behavior.
Jul
15
asked Is the prox-residual monotone?
Jul
15
asked Geometric measures different from Hausdorff
Jul
14
awarded  Nice Question
Jul
12
comment Heuristic interpretation of the 'third index' for Besov and Triebel-Lizorkin spaces
Finally somebody asked this here! (I wonder why I did not…)
Jul
5
reviewed Approve suggested edit on What is natural about the well-known bijection between conjugacy classes and irreps of a symmetric group?
Jul
4
answered Mathematicians who made important contributions outside their own field?
Jul
2
awarded  Curious
Jun
26
answered Relativistic Control Theory
Jun
19
answered Discrete gradient on point clouds
Jun
17
answered Roots of modified polynomials
Jun
15
comment Why are polynomials so useful in mathematics?
I would phrase the first reason for the usefulness of quadratics as "They imply a notion of positivity".