bio  website  regularize.wordpress.com 

location  Braunschweig, Germany  
age  35  
visits  member for  3 years, 9 months 
seen  2 hours ago  
stats  profile views  1,619 
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 PernaLions 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 proxresidual monotone? 
Jul 16 
comment 
Is the proxresidual monotone?
Great, thanks! Somehow, my examples where either somehow isotropic or random and did not show this behavior. 
Jul 15 
asked  Is the proxresidual 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 TriebelLizorkin spaces
Finally somebody asked this here! (I wonder why I did not…) 
Jul 5 
reviewed  Approve suggested edit on What is natural about the wellknown 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". 