bio  website  regularize.wordpress.com 

location  Braunschweig, Germany  
age  36  
visits  member for  4 years, 1 month 
seen  13 hours ago  
stats  profile views  1,745 
Professor at TU Braunschweig.
Area: Inverse problems, regularization theory, applied functional analysis, mathematical image processing.
18h

comment 
Minimal surface dividing a simply connected region into two regions of equal volume
possible duplicate of Minimal surface which divides a convex body into two regions of equal volume, I don't see how this question differs from the one you linked. 
1d

reviewed  Leave Open “Almost” zeta function 
2d

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… 
2d

revised 
Removing constraints in convex optimization
Extended and corrected 
2d

comment 
What's the idea behind various equivalent norms on Besov spaces $B^{s}_{p,q}$?
Another book that is quite detailed is Runst and Sickel's Sobolev Spaces of Fractional Order, Nemytskij Operators, and Nonlinear Partial Differential Equations. However, I guess for the equivalence of the norms they refer to Triebel… 
2d

comment 
Geometric measures different from Hausdorff
Thanks a lot for the answer, especially for pointin to Frostman's lemma, densities and the example where $H^m(A)>0$ and $G_m(A) = 0$. This is exactly in the direction I was hoping. If you had additonally some concrete examples where Hausdorff, Dyadic and Spherical Measure differ I would accept and cash the bounty right away! 
Nov 18 
reviewed  Close measures of global stability 
Nov 18 
reviewed  Leave Open How to prove that a kernel is positive definite? 
Nov 17 
answered  Removing constraints in convex optimization 
Nov 14 
reviewed  Approve suggested edit on Graph automorphism that swaps two pairs of nodes 
Nov 14 
reviewed  Leave Open RIP, NSP and Spark of A Matrix 
Nov 14 
answered  Standard names and methods for this type of fitting minimization 
Nov 14 
comment 
Noncommutative version of Littlewood's First Principle
While the title sounds interesting to me, I have to admit that I don't have any idea what this "noncommutative setting" you are talking about may be, let alone what an analog of Littlewood's principle may be. 
Nov 13 
comment 
Does the boundary of a convex body contain a regular planar pentagon?
Does a convex body need to have nonempty other interior? Otherwise the answer is no. 
Nov 12 
revised 
Is the boundary $\partial S$ analogous to a derivative?
Corrected typos. Extended answer a bit. 
Nov 11 
comment 
RIP, NSP and Spark of A Matrix
Hint: the NSP does not change if you scale the columns of the matrix but the RIP constant can go to zero under scaling. 
Nov 11 
comment 
RIP, NSP and Spark of A Matrix
All these notions arise in compressed sensing (hence the tag). 
Nov 9 
comment 
Area of the minimal surface of a nonplanar quadrilateral in 3d
Regarding your other comment: I thought 'minimal surface' would mean 'surface of minimal area' but probably there are some local minima (whatever this means in this context)? 
Nov 9 
comment 
Area of the minimal surface of a nonplanar quadrilateral in 3d
A formula in elliptic functions or another nonelementary integral would be OK. In the end I would be happy with a simple numerical method to calculate the value. 
Nov 7 
asked  Area of the minimal surface of a nonplanar quadrilateral in 3d 