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Random lattice always has trivial automorphism group?

In example 2.5 of a paper [LS17] written by Lenstra and Silverberg, it is written that “Random” lattices have $Aut(L) = \{ \pm 1 \}$, I guess the 'Random' here refers to the distribution in Siegel's ...
constantine's user avatar
6 votes
1 answer
180 views

Expected value of the length of the shortest non-zero vector in a lattice?

$\DeclareMathOperator\SL{SL}$What is the expected value of the length of the shortest non-zero vector in a (unimodular) lattice? I.e., let $G=\SL_n(\mathbb{R})$ with Haar measure $\mu$, $\Gamma=\SL_n(...
yoyo's user avatar
  • 609
9 votes
1 answer
735 views

Where has this structure been observed?

$\newcommand{\M}{\mathcal{M}}$Let $M$ be a monoid. Consider the following structure: $R_X,R_Y:\mathbb{Z}^2 \to M$ satisfying the following "compatiblity-relation": $$R_X (x, y) \cdot R_Y (x +...
Asaf Shachar's user avatar
  • 6,741
1 vote
0 answers
78 views

Canonical representation of the a probability distribution for Hammersley Clifford Theorem

I'm reading the following paper http://www2.stat.duke.edu/~scs/Courses/Stat376/Papers/GibbsFieldEst/BesagJRSSB1974.pdf On page 7 they give the result that $$Q(\textbf{x}) = \sum_{1 \leq i \leq n} ...
Pavan Sangha's user avatar
3 votes
0 answers
185 views

Lattice points in a rotated product-of-balls

Fix $U$ unitary over $\mathbb{R}^{K},$ take $U_n=I_{n\times n}\otimes U$ and denote the unit ball at 0 in $\mathbb{R}^n$ as $B^n$. For $d_1,\dots,d_K>0$, fix $S_n:=U_n\left(\prod_{k=1}^K d_k B^n\...
Christian Chapman's user avatar
27 votes
7 answers
9k views

Why are two "random" vectors in $\mathbb R^n$ approximately orthogonal for large $n$?

I saw that two random independent vectors are approximately orthogonal in high dimensional space. How can I prove this? And is there an intuitive explanation? Thank you.
YONGSEEN KIM's user avatar
1 vote
1 answer
242 views

Two types of random walkers on square lattice

Consider a two dimensional square lattice ($n$ by $n$), which is our space $S$ (each point labelled by an index $1\to n^2$), containing two types of particles, distinguished here by either an index $1$...
user avatar
6 votes
3 answers
425 views

Probability a random matrix contains a short integer vector in its kernel

Consider a random $m$ by $n$ matrix $M$ with $m \leq n$, chosen uniformly over all those whose elements are in $\{0,1\}$ (or $\{-1,1\}$ if it is any easier). Is there any mathematical theory that ...
Simd's user avatar
  • 3,377
4 votes
1 answer
829 views

Probability that a "closable" self-avoiding random walk forms a polygon

Consider a self-avoiding random walk on an infinite graph (for concreteness, the grid of 2-dimensional lattice points $\mathbb{Z}^2$), in which on each step, the next position is chosen uniformly at ...
Mechanical snail's user avatar
11 votes
2 answers
466 views

Defining measures over frames in place of $\sigma$-algebras

Normally, measures and probability spaces are defined over $\sigma$-algebras. I was wondering what would happen if one tries to define it over frames in place of $\sigma$-algebras? Specifically, ...
Kaveh's user avatar
  • 5,502
1 vote
1 answer
555 views

The probability a self-avoiding random walk (SAW) on a rectangular or hexagonal lattice takes more than $N$ steps before trapping itself

What is the probability that a self-avoiding random walk (SAW) on a rectangular or hexagonal lattice is able to take more than $N$ steps, i.e. able to take more than $N$ steps before trapping itself ...
CKura's user avatar
  • 55
2 votes
1 answer
267 views

Expected number of identical vertex pairs with the same Euclidean distance on a randomly colored rectangular lattice

Imagine I have an $N$ by $M$ rectangular lattice where I randomly assign one of $k$ colors to every vertex in the lattice. I then write down a list of the ${N*M}\choose{2}$ possible unordered pairs ...
Polyrhythm's user avatar
16 votes
4 answers
597 views

The lattice spanned by $m$ random 0-1 vectors of length $n$

Consider $m$ random 0-1 vectors of length $n$. Let $L$ be the lattice spanned by them. What is the value of $m$ (as a function of $n$) for which it is true with positive probability that $L=Z^n$? More ...
Gil Kalai's user avatar
  • 24.7k
0 votes
1 answer
289 views

Dither in Leech lattice quantization!

Can you please help me how to generate a dither signal $\mathbf{U}$, where $\mathbf{U}$ is a random vector of length 24 that is uniformly distributed over the Voronoi region of the Leech lattice. Best,...
Farzad's user avatar
  • 197
10 votes
3 answers
644 views

Models with SLE scaling limit

What discrete processes/models have been proven to have scaling limits to $\text{SLE}(\kappa)$, for various $\kappa$? I know about loop-erased random walk and uniform spanning trees. What about ...
Gjergji Zaimi's user avatar