bio  website  suvrit.de 

location  Internet  
age  
visits  member for  4 years, 3 months 
seen  14 hours ago  
stats  profile views  8,509 
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 semimetric 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 areaminimizing 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 blockmatrix 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? 