1,021 reputation
213
bio website uni-ulm.de/en/mawi/analysis/…
location Germany
age 35
visits member for 1 year, 7 months
seen 2 hours ago

I work on evolution equations, sometimes on their applications too. I am interested in PDEs and functional analysis. I am fond of algebraic graph theory.


4h
comment Recreating the wheel
I share Ben McKay's opinion, but once it happened to me that my collaborator and I re-found a theorem with exactly the very same proof found by a math physicist more than 30 years earlier. We discovered this by chance, googling for something different. At the end we decided to generalize his result taking advantage of some functional analytical notions that had appeared since then, but clearly we were much less motivated to work on it after this discovery.
5h
comment Estimate infinity norm with Lp and W1p norm
sorry, year -> here. amazing typo.
1d
comment Estimate infinity norm with Lp and W1p norm
@Deane Yang: But $n=1$ year, isn't it?
1d
comment a class of directed hypergraphs
thanks. but i was looking exactly for a refinement of rusnak's concepts. in my post, i used the word "directed" as a sloppy synonym of your "oriented". it was the further condition the one that really matters.
1d
answered Estimate infinity norm with Lp and W1p norm
1d
asked a class of directed hypergraphs
Apr
13
comment Laplacian matrix of a graph with negative weights
I am sorry, but I do not understand your question yet. The Laplacian is just a matrix defined in a certain way, and its introduction goes back to Kirchhoff. At a certain point in the history (around 1970) people started noticing this matrix was tightly connected with the "usual" Laplacian on domains. If you are interested in some historical remarks, you can take a look at the notes at the end of Chapter 2 of this monograph: uni-ulm.de/fileadmin/website_uni_ulm/mawi.inst.010/mugnolo/…
Apr
13
comment Laplacian matrix of a graph with negative weights
Concerning your first question: What do you mean by "references"? It is a definition. But a standard one, if you mean this: Take a look in Biggs' book, Godsil-Royle's book, Mohar's surveys, etc. Yes, loops are generally very problematic when it comes to defining Laplacians, even if no weights are assigned.
Apr
12
answered Laplacian matrix of a graph with negative weights
Apr
11
revised Riemannian metric and Volume form for $SE(n)$ and/or $E(n)$
corrected spelling
Apr
11
suggested suggested edit on Riemannian metric and Volume form for $SE(n)$ and/or $E(n)$
Apr
8
answered Existence for ODE in Banach space (accretive operators and Crandall-Liggett)
Mar
4
comment Besicovitch Almost Periodic Functions a subspace of what?
also, I would refrain from calling this the common example of a nonseparable Hilbert space.
Feb
28
comment $2$-normed Spaces
my first guess would have been that $N(x,y)$ is just another way of writing $\|x-y\|$ for a suitable norm $\|\cdot\|$, but then i saw (3) and (4)...
Feb
21
comment parabolic PDE with almost-monotone elliptic operator, existence results?
I am not sure to understand. That convergence is automatic if your functional satisfies the assumption of that theorem (coercivity etc.). And those assumptions are of course formulated thinking of a relatively general parabolic setting. How comes that that convergence fails? Do you have an oscillating behaviour as $m\to\infty$?
Feb
18
answered parabolic PDE with almost-monotone elliptic operator, existence results?
Feb
18
comment parabolic PDE with almost-monotone elliptic operator, existence results?
Are you thinking of a linear $A$? Should $V$ be a Hilbert space as in the usual notion of Gel'fand triple?
Feb
14
revised Linear dynamical systems: interpretation of Frobenius eigenvector
edited body
Feb
14
answered Linear dynamical systems: interpretation of Frobenius eigenvector
Feb
11
revised Eigenvectors and partitions of graphs
fixed formatting in a math formula and was additionally forced to change the wording in a sentence to let mathoverflow accept my first edit.