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32675
bio website suvrit.de
location Internet
age
visits member for 4 years, 3 months
seen 14 hours ago

Researcher in Optimization, Machine Learning, etc.

Hobbyist in a small fraction of the world of Inequalities, Matrix Analysis, Noncommutative polynomials.

I'm here mostly to learn old and new mathematics!


1d
reviewed Close independent subset problems
Nov
19
reviewed Close A new method of solutions for partial linear differential equations
Nov
19
reviewed Close Noncommutative version of Littlewood's First Principle
Nov
18
comment Is the product of sine principal angles a semi-metric on Grassmannian?
Say $U'U=I_d$ and $V'V=I_d$, then unless I'm completely overseeing something obvious, it is pretty easy to find counterexamples to the triangle inequality.
Nov
17
reviewed Leave Open Can an algorithm decide whether a program computes all strings?
Nov
17
reviewed Close Hadamard perturbations to the determinant
Nov
15
reviewed Close Necessary Condition For Ellipticity
Nov
15
reviewed Close Partial differential equation
Nov
15
reviewed Leave Open How to prove that a kernel is positive definite?
Nov
14
answered How to prove that a kernel is positive definite?
Nov
12
comment Combinatorial Interpretation of Generalized Stirling numbers
did you try at least googling?
Nov
9
reviewed Close Minimal surfaces are area-minimizing in small balls
Nov
6
awarded  Nice Answer
Nov
6
revised Eigenvectors of a particular transition matrix
added proof of eigenvalues; removed intuition behind the discovery of the solution.
Nov
3
comment Proving that the kernel of this matrix is of dimension 2
You may benefit from looking at: repository.uwyo.edu/cgi/… and perhaps this tiny writeup: arxiv.org/abs/1201.4651
Nov
1
comment The formula for a perhaps basic identity (move from stackexchange)
So in other words, this is $\prod_l\det(P_l)$, where $P_l$ is a diagonal matrix with entries $[1+x_l+y_i]_{i=1}^n$; i.e., $\det(P_1\cdots P_m)$. But expanding out the products seems to not be so cool; perhaps working with $\sum_{kl}\log ...$ may be more helpful.
Oct
31
comment Eigenvectors of a particular transition matrix
@darijgrinberg: Good suggestion. I'll spend some time over the weekend to clean up the post, and put the heuristics into the background. Thanks!!
Oct
31
comment Eigenvectors of a particular transition matrix
@darijgrinberg: actually, scratch all the other stuff; I remembered that actually $V=\exp(L_n)$ above turns $P^{-1}$ into an upper triangular matrix, from which one can immediately read off the eigenvalues of $P^{-1}$, no need to go over to $P^{-2}$, which I had to do when trying to get the eigenvectors!
Oct
31
comment Determinant of a determinant
Would be interesting if we could exploit the usual (complex field) fact that $\det(A)=\wedge^n A$, and the block-matrix lemma mentioned here: mathoverflow.net/questions/173088/… by extracting wedge products of individual blocks as principal submatrices of the wedge products of the entire matrix (these relations don't seem to depend on having a field)
Oct
29
comment Product $PVPVP$ is elementwise nonnegative?
@cardinal: please excuse my slowness, but is it then immediate that one gets elementwise nonnegativity?