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In this article, we study short intervals that contain another type of "almost square", an integer $n$ which can be factored in two different ways $n = a_1 b_1 = a_2 b_2$ with $a_1, a_2, b_1, b_2$ close to $\sqrt{n}$.

Number Theory · Mathematics 2007-05-23 Tsz Ho Chan

Classical two-sample permutation tests for equality of distributions have exact size in finite samples, but they fail to control size for testing equality of parameters that summarize each distribution. This paper proposes permutation tests…

Econometrics · Economics 2022-04-22 Marinho Bertanha , EunYi Chung

We propose a new approach to conjugation-invariant random permutations. Namely, we explain how to construct uniform permutations in given conjugacy classes from certain point processes in the plane. This enables the use of geometric tools…

Probability · Mathematics 2025-11-13 Victor Dubach

Let $k$ be a nonnegative integer, and let $\alpha$ and $\beta$ be two permutations of $n$ symbols. We say that $\alpha$ and $\beta$ $k$-commute if $H(\alpha\beta, \beta\alpha)=k$, where $H$ denotes the Hamming metric between permutations.…

Combinatorics · Mathematics 2017-09-06 Rutilo Moreno , Luis Manuel Rivera

Answering a question of Clark and Ehrenborg (2010), we determine asymptotics for the number of permutations of size n that admit the most common excedance set. In fact, we provide a more general bivariate asymptotic using the multivariate…

Combinatorics · Mathematics 2016-05-30 Rodrigo Ferraz de Andrade , Erik Lundberg , Brendan Nagle

A square is a factor $S = (S_1; S_2)$ where $S_1$ and $S_2$ have the same pattern, and a permutation is said to be square-free if it contains no non-trivial squares. The permutation is further said to be bicrucial if every extension to the…

Combinatorics · Mathematics 2022-01-31 Carla Groenland , Tom Johnston

We consider the enumeration of pattern-avoiding involutions, focusing in particular on sets defined by avoiding a single pattern of length 4. As we demonstrate, the numerical data for these problems demonstrates some surprising behavior.…

Combinatorics · Mathematics 2014-09-15 Miklós Bóna , Cheyne Homberger , Jay Pantone , Vincent Vatter

There is a deep connection between permutations and trees. Certain sub-structures of permutations, called sub-permutations, bijectively map to sub-trees of binary increasing trees. This opens a powerful tool set to study enumerative and…

Combinatorics · Mathematics 2014-07-02 Filippo Disanto , Thomas Wiehe

In this paper we study the asymptotic behavior of linear processes having as innovations mean zero, square integrable functions of stationary reversible Markov chains. In doing so we shall preserve the generality of coefficients assuming…

Probability · Mathematics 2012-06-05 Magda Peligrad

We extend Stanley's work on alternating permutations with extremal number of fixed points in two directions: first, alternating permutations are replaced by permutations with a prescribed descent set; second, instead of simply counting…

Combinatorics · Mathematics 2007-06-22 Guo-Niu Han , Guoce Xin

We study the optimal rectangular-discrepancy approximation of permutons by finite permutations. We transfer bounds from discrepancy theory to this more restricted setup. Moreover, we show that superlinear approximation can occur only for…

Combinatorics · Mathematics 2026-05-05 Balázs Maga

An infinite permutation is a linear ordering of the set of natural numbers. An infinite permutation can be defined by a sequence of real numbers where only the order of elements is taken into account. In the paper we investigate a new class…

Combinatorics · Mathematics 2016-12-15 Sergey V. Avgustinovich , Anna E. Frid , Svetlana Puzynina

Define $S_n^k(T)$ to be the set of permutations of $\{1,2,...,n\}$ with exactly $k$ fixed points which avoid all patterns in $T \subseteq S_m$. We enumerate $S_n^k(T)$, $T \subseteq S_3$, for all $|T| \geq 2$ and $0 \leq k \leq n$.

Combinatorics · Mathematics 2007-05-23 Toufik Mansour , Aaron Robertson

We investigate the asymptotic properties of permutations drawn from the Luce model, a natural probabilistic framework in which permutations are generated sequentially by sampling without replacement, with selection probabilities…

Probability · Mathematics 2025-10-07 Jacopo Borga , Sourav Chatterjee , Persi Diaconis

We determine a set of permutation patterns $q$ so that the number of permutations with $r$ occurrences of $q$ is asymptotically $n^r$ times the number of permutations avoiding $q$, partially settling a conjecture of Conway and Guttman. We…

Combinatorics · Mathematics 2026-03-24 Michael Waite

In this paper we study the inverse of so-called unfair permutations, and explore various properties of them. Our investigation begins with comparing this class of permutations with uniformly random permutations, and showing that they behave…

Probability · Mathematics 2018-06-01 İlker Arslan , Ümit Işlak , Cihan Pehlivan

We consider a random permutation drawn from the set of 132-avoiding permutations of length $n$ and show that the number of occurrences of another pattern $\sigma$ has a limit distribution, after scaling by $n^{\lambda(\sigma)/2}$ where…

Probability · Mathematics 2016-05-25 Svante Janson

Let $G_{k,n}$ be a group of permutations of $kn$ objects which permutes things independently in disjoint blocks of size $k$ and then permutes the blocks. We investigate the probabilistic and/or enumerative aspects of random elements of…

Probability · Mathematics 2025-04-29 Persi Diaconis , Nathan Tung

Consider a random permutation of $kn$ objects that permutes $n$ disjoint blocks of size $k$ and then permutes elements within each block. Normalizing its cycle lengths by $kn$ gives a random partition of unity, and we derive the limit law…

Combinatorics · Mathematics 2026-01-06 Nathan Tung

Recall that a Stirling permutation is a permutation on the multiset $\{1,1,2,2,\ldots,n,n\}$ such that any numbers appearing between repeated values of $i$ must be greater than $i$. We call a Stirling permutation ``flattened'' if the…

Combinatorics · Mathematics 2023-11-29 Adam Buck , Jennifer Elder , Azia A. Figueroa , Pamela E. Harris , Kimberly Harry , Anthony Simpson