Per Alexandersson

Zurich, Switzerland

www2.math.su.se/~per

Age: 27

Currently interested in Schur functions and semistandard Young tableaux and misc. related representation theory and combinatorics.

Phd thesis defended 2013, titled Combinatorial Methods in Complex Analysis.

I keep an eye out for interesting results related to complex dynamics, computability, and computer-assisted research. I use Mathematica extensively in my research. My other main programming languages are Java, LaTeX, PHP, C, etc.

18h
comment A game of stones
@LiviuNicolaescu: That's nice! Perhaps if the stone density of the smallest interval containing all stones goes to zero, there is a positive solution? That is, if $f \sim n^{1+\epsilon}$. Seems like one might be able to do a probabilistic argument from this.
18h
comment Estimating the moments of a random variable
Can you give a concrete example that you have in mind?
21h
revised A game of stones
added 925 characters in body
21h
comment A game of stones
Ah, yes, there is some issue; I will rephrase it as a reduction of the problem, but it does not solve it completely.
23h
comment Could there be an exact formula for the Ramsey numbers?
Somehow, this makes me think of pattern avoidance: en.wikipedia.org/wiki/Permutation_pattern The permutations that avoid the pattern 1324 is still unknown, and finding a formula for these is according to some, a really tough question (I recall Zeilberger compares this to RH)....
1d
answered A game of stones
1d
reviewed Approve suggested edit on State of the art in the theory of integer sequences
1d
comment State of the art in the theory of integer sequences
You want to read this wiki page: en.wikipedia.org/wiki/Holonomic_function This is essentially the class of functions that software can detect automatically.
Nov
19
answered What is "graph-directed iterated function"?
Nov
19
comment What is "graph-directed iterated function"?
So, for those that want to see wiki link: en.wikipedia.org/wiki/Rauzy_fractal
Nov
18
comment "Nyldon words": understanding a class of words factorizing the free monoid increasingly
Looks like in many (but not all) cases, $a_1a_2\dots a_n$ is a Nyldon word, then $a_2\dots a_n a_1$ is a Lyndon word. But this is not entirely true... But maybe a bijection can start from this?
Nov
18
comment Are the moves/rules of standard chess delicately balanced?
Another point to make is that we would not discuss chess if it was not interesting. People invent new games all the time, but only the interesting ones "survives".
Nov
18
comment "Nyldon words": understanding a class of words factorizing the free monoid increasingly
Are the sets of Lyndon words and Nyldon words of length $n$ of same cardinality? Maybe there is a simple bijective proof of these conjectures.
Nov
17
comment Decomposing polyhedral cones into "direct sums" and a polynomial
The polynomial, it looks quite close to the denominator in the Ehrhart series... Could it be something obtained from that?
Nov
17
comment A hard combinatorial identity
Zeilbergers algorithm is build-in in Maple. GIYF. maplesoft.com/support/help/Maple/view.aspx?path=SumTools/…
Nov
17
comment Are the moves/rules of standard chess delicately balanced?
Making an analogy with the categorization of one-dimensional cellular automata in Wolframs NKS, it would not be surprising if a positive fraction of all "random" chess variants with fairy pieces have the properties you ask for.
Nov
14
comment Regular unimodular triangulation for a certain simplex
Yeah, it is not clear to me either, actually, now when you mention it... but somehow, the triangulation is so nice, so that I would find it difficult not to be in some sense.. but yes, this is a gap.
Nov
14
revised Regular unimodular triangulation for a certain simplex
added 66 characters in body
Nov
14
comment Regular unimodular triangulation for a certain simplex
Ah, you are right! I realized I asked the wrong question. This is the solution to the problem I had in mind, I should edit one of them... Or perhaps delete both...
Nov
14
comment Under what circumstances would a professor be offended at students taping or recording his or her lecture?
Cdaragorn: I disagree. There are children, for example, that go to school, that are under protection, and they are of course not responsible. It is common courtesy to ask for permission before videotaping at a non-public location.
1 2 3 4 5