7,254 reputation
12554
bio website fa.its.tudelft.nl/~teuwen
location Delft, Netherlands
age 27
visits member for 3 years, 11 months
seen Aug 5 '13 at 10:51

About me

I'm a PhD candidate in analysis (harmonic analysis). I have a Master of Science degree in mathematics (analysis).

I am interested in many topics in analysis, but in particular: harmonic analysis, functional analysis, operator theory and special functions.

My email address is jonasteuwen@gmail.com.

I would appreciate it if you would correct my spelling and grammatical errors.


Me elsewhere


Jun
6
comment Who's doing stochastic calculus on manifolds in the Netherlands on a professional level?
@Aris: Yes. If you can find some people that would like to learn something from the other field as well that should be fine.
Jun
3
comment Who's doing stochastic calculus on manifolds in the Netherlands on a professional level?
Nobody. You might have more luck in Australia (Pierre Portal, Canberra). In The Netherlands you could have financial math people or real mathematicians. Onno van Gaans in Leiden (no manifolds, I believe). Mark Veraar and Jan van Neerven in Delft (on Banach spaces). Do remember funding will be a big problem.
Jan
8
comment On the regularity of the Laplace equations and tensor products and such
Alright - thanks. Indeed, this is what I figured since I asked the question. But then I was wondering 'how bad' this could be - as in a splitting in a good and a bad part. Different question so I'll accept this.
Jan
8
comment On the regularity of the Laplace equations and tensor products and such
Alright, I seem to be totally misunderstanding things, so I have written how I think it is (but first: lunch). (I'll look at your edit later).
Jan
8
comment On the regularity of the Laplace equations and tensor products and such
In any case, I have rewritten it slightly. I do not want people to assume I am that stupid that I think tensor spaces are that trivial.
Jan
8
comment On the regularity of the Laplace equations and tensor products and such
@WillieWong I will rewrite it if you still think it is a 'logical fallacy' after my comment!
Jan
8
comment On the regularity of the Laplace equations and tensor products and such
Oops - logical fallacy is for me more like a error in verbal reasoning -. Anyway, I meant to say that it is a dense set in the tensor product. That is, a Schauder basis. Is that not true? When we separate we can find sequences of basis functions and then we construct the basis for the solution space as a Schauder basis.
Jan
4
comment Does there exist a diagonal dominance concept for integral kernels?
On every inner product space every self-adjoint operator $P$is positive if for all non-zero $u$ we have $\langle Pu, u \rangle > 0$.
Jan
4
comment Does there exist a diagonal dominance concept for integral kernels?
@SimenK. But, I do not see understand why my decomposition would not be the way to proceed. Self-adjointness amounts to real eigenvalues and so on.
Jan
3
comment Does there exist a diagonal dominance concept for integral kernels?
So, is the question about the positivity of Hilbert-Schmidt operators? Hit it with the spectral theorem to decouple your kernel in that case.
Jan
3
comment Growth $\beta X\setminus X$ of a Banach space $X$
Yes, thank you for the link. I had something like that in mind - Topologically dualize a test function space and sqeeuze the Banach space in between.
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
Nothing. Does that answer your question 8-)? I would like to know what $\beta W_0^{m, p}\setminus W_0^{m, p}$ is nevertheless.
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
At least it was stupid enough for someone to downvote it! I will attempt to phrase the question in a more meaningful way.
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
I wish to figure out how common this phenomenon is. It is clear that I cannot make $W^{m, p}$ larger in this sense as that would involve things having non-finite norm. But I can make $W_0^{m, p}$ --which is as much Banach as $W^{m, p}$-- larger. I am starting to wonder if the question would be of enough 'level' to ask on MO. I did not as I might need to be able to phrase it better...
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
@JonasMeyer Yes. As in my Sobolev space, if I take the circle and functions with compact support on the circle and take the closure in the norm $W^{m, p}$ where the functions are at least $C^m$ then I get a different space than if I start with $C^m$ functions without the compact support. Namely, the first space will have functions with trace null, whereas the second one will have much more. They only coincide whenever the complement if their domain is $(m , q)$-polar. Both norms make sense. But $W_0^{m, p}$ is a strict subset.
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
@JonasMeyer I had in mind the above Sobolev spaces on domains where one only can describe Dirichlet problems. I need to figure out how to characterize that.
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
@JonasMeyer Yes, I think I must have misunderstood the reply. I do want $X$ to at least continuously be included in $Y$. It is quite a simple example and was not really what I had in mind. Showing that Banach spaces are not so easy to grasp intuitively! :-). So you have understood the question!
Jan
2
comment Initial segments order-isomorphic
It is quite peculiar someone went through the trouble of downvoting this like today.
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
suPset. I do know a little bit of elementary metric space theory. Maybe not that much, but at least that...
Jan
2
comment Growth $\beta X\setminus X$ of a Banach space $X$
Ah - I see! But separable spaces are usually not the interesting cases. $L^\infty$? I would be quite surprised if you now tell me all non-separable ones are homeomorphic as well!