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13 votes
2 answers
398 views

Expected sorting time of random permutation using random comparators

In sorting networks, a comparator of positions $i < j$ is an operator which takes a permutation, checks if $p_i > p_j$, and if it is the case, swaps $p_i$ and $p_j$. Using this, we can define ...
Daniel Weber's user avatar
  • 3,319
3 votes
1 answer
134 views

Cycle counts in Ewens measure as $\theta$ diverges

For $w$ a permutation, let $c(w)$ denote the total number of cycles and $c_i(w)$ denote the number of $i$-cycles. The Ewens measure is a one-parameter probability distribution on permutations where ...
Zach H's user avatar
  • 1,989
1 vote
1 answer
124 views

Tight estimates for binomial summation

Is there tight estimates for the following logarithmic summation ($\gamma\in(0,1)$) $$\ln\Bigg(\sum_{t=\frac{n^{}}2-\gamma n^\gamma}^{\frac{n^{}}2+\gamma n^\gamma}\sum_{\ell=\frac{n^{}}2-\gamma n^\...
VS.'s user avatar
  • 1,826
3 votes
0 answers
395 views

Sum of random permutation matrices

Let $A$ be a uniformly random $k\times k$ permutation matrix, and $A_1,\ldots, A_m$ be the $m$ independent copies of $A$. Here the uniform distribution is with respect to the $k!$ possible permutation ...
Minkov's user avatar
  • 1,127
18 votes
3 answers
2k views

What is the probability that two random permutations have the same order?

I am interested in the orders of random permutations. Since the law of the logarithm of the order of a permutation converges to a normal law (for instance Erdös-Turan Statistical group theory III), ...
thibo's user avatar
  • 333
1 vote
0 answers
243 views

Factorization of permutations.

Let $n,k$ be positive integers such that $3n=2k$ and $N = \lfloor \alpha n\rfloor$ for some constant $0<\alpha<1$. Let $S_{3n}$ denote the permutation group of order $3n$. Consider the following ...
gmath's user avatar
  • 141