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Pattern avoiding machines were recently introduced by Claesson, Ferrari and the current author to gain a better understanding of the classical $2$-stacksort problem. In this paper we generalize these devices by allowing permutations with…

Combinatorics · Mathematics 2020-04-22 Giulio Cerbai

We demonstrate a natural bijection between a subclass of alternating sign matrices (ASMs) defined by a condition on the corresponding monotone triangle which we call the gapless condition and a subclass of totally symmetric…

Combinatorics · Mathematics 2012-08-28 Arvind Ayyer , Robert Cori , Dominique Gouyou-Beauchamps

In this paper, we consider cyclic permutations that avoid the monotone decreasing permutation $k(k-1)\ldots 21$, whose cycle also demonstrates some pattern avoidance. If the cycle is written in standard form with 1 appearing at the…

Combinatorics · Mathematics 2024-08-28 Kassie Archer , Ethan Borsh , Jensen Bridges , Christina Graves , Millie Jeske

We have extended classical pattern avoidance to a new structure: multiple task-precedence posets whose Hasse diagrams have three levels, which we will call diamonds. The vertices of each diamond are assigned labels which are compatible with…

Combinatorics · Mathematics 2023-06-22 Mitchell Paukner , Lucy Pepin , Manda Riehl , Jarred Wieser

We investigate pattern-avoiding (0,1)-matrices as generalizations of pattern-avoiding permutations. Our emphasis is on 123-avoiding and 321-avoiding patterns for which we obtain exact results as to the maximum number of 1's such matrices…

Combinatorics · Mathematics 2020-05-06 Richard A. Brualdi , Lei Cao

In the context of the genome rearrangement problem, we analyze two well known models, namely the block transposition and the prefix block transposition models, by exploiting the connection with the notion of permutation pattern. More…

Combinatorics · Mathematics 2018-08-09 Giulio Cerbai , Luca Ferrari

Zimin words are very special finite words which are closely related to the pattern-avoidability problem. This problem consists in testing if an instance of a given pattern with variables occurs in almost all words over any finite alphabet.…

Data Structures and Algorithms · Computer Science 2013-07-08 Radosław Głowinski , Wojciech Rytter

In combinatorics on words, a word w over an alphabet Sigma is said to avoid a pattern p over an alphabet Delta if there is no factor x of w and no non-erasing morphism h from Delta^* to Sigma^* such that h(p) = x. Bell and Goh have recently…

Combinatorics · Mathematics 2009-07-28 Narad Rampersad

We characterize separable multidimensional permutations in terms of forbidden patterns and enumerate them by means of generating function, recursive formula and explicit formula. We find a connection between multidimensional permutations…

Combinatorics · Mathematics 2008-03-25 Andrei Asinowski , Toufik Mansour

We complete the Wilf classification of signed patterns of length 5 for both signed permutations and signed involutions. New general equivalences of patterns are given which prove Jaggard's conjectures concerning involutions in the symmetric…

Combinatorics · Mathematics 2008-01-22 Mark Dukes , Vit Jelínek , Toufik Mansour , Astrid Reifegerste

We survey permutation-based methods for approximate k-nearest neighbor search. In these methods, every data point is represented by a ranked list of pivots sorted by the distance to this point. Such ranked lists are called permutations. The…

Machine Learning · Computer Science 2016-11-01 Bilegsaikhan Naidan , Leonid Boytsov , Eric Nyberg

A permutation p is realized by the shift on N symbols if there is an infinite word on an N-letter alphabet whose successive left shifts by one position are lexicographically in the same relative order as p. The set of realized permutations…

Combinatorics · Mathematics 2009-09-15 Sergi Elizalde

Permutations that avoid given patterns have been studied in great depth for their connections to other fields of mathematics, computer science, and biology. From a combinatorial perspective, permutation patterns have served as a unifying…

Combinatorics · Mathematics 2023-06-22 Sylvie Corteel , Megan A. Martinez , Carla D. Savage , Michael Weselcouch

In this paper, we study the distribution of consecutive patterns in the set of 123-avoiding permutations and the set of 132-avoiding permutations, that is, in $\mathcal{S}_n(123)$ and $\mathcal{S}_n(132)$. We first study the distribution of…

Combinatorics · Mathematics 2019-01-07 Ran Pan , Dun Qiu , Jeffrey Remmel

Inspired by the results of Baik, Deift and Johansson on the limiting distribution of the lengths of the longest increasing subsequences in random permutations, we find those limiting distributions for pattern-restricted permutations in…

Combinatorics · Mathematics 2009-09-29 Emeric Deutsch , A. J. Hildebrand , Herbert S. Wilf

Let $\pi_n$ be a uniformly chosen random permutation on $[n]$. Using an analysis of the probability that two overlapping consecutive $k$-permutations are order isomorphic, the authors of a recent paper showed that the expected number of…

Combinatorics · Mathematics 2024-08-07 Anant Godbole , Hannah Swickheimer

In a recent paper, Backelin, West and Xin describe a map $\phi ^*$ that recursively replaces all occurrences of the pattern $k... 21$ in a permutation $\sigma$ by occurrences of the pattern $(k-1)... 21 k$. The resulting permutation…

Combinatorics · Mathematics 2008-05-05 Mireille Bousquet-Melou , Einar Steingrimsson

We study the feasible region for consecutive patterns of pattern-avoiding permutations. More precisely, given a family $\mathcal C$ of permutations avoiding a fixed set of patterns, we consider the limit of proportions of consecutive…

Combinatorics · Mathematics 2025-09-10 Jacopo Borga , Raul Penaguiao

We show that permutations of size $n$ avoiding both of the dashed patterns 32-41 and 41-32 are equinumerous with indecomposable set partitions of size $n+1$, and deduce a related result.

Combinatorics · Mathematics 2014-05-09 David Callan

Let T_k^m={\sigma \in S_k | \sigma_1=m}. We prove that the number of permutations which avoid all patterns in T_k^m equals (k-2)!(k-1)^{n+1-k} for k <= n. We then prove that for any \tau in T_k^1 (or any \tau in T_k^k), the number of…

Combinatorics · Mathematics 2007-05-23 T. Mansour
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