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Building off recent work of Garg and Peng, we continue the investigation into classical and consecutive pattern avoidance in rooted forests. We prove a forest analogue of the Stanley-Wilf conjecture for avoiding a single pattern as well as…

Combinatorics · Mathematics 2023-10-05 Michael Ren

Following Anders and Archer, we say that an unordered rooted labeled forest avoids the pattern $\sigma\in\mathcal{S}_k$ if in each tree, each sequence of labels along the shortest path from the root to a vertex does not contain a…

Combinatorics · Mathematics 2022-11-01 Swapnil Garg , Alan Peng

In this paper, we study the Wilf-type equivalence relations among multiset permutations. We identify all multiset equivalences among pairs of patterns consisting of a pattern of length three and another pattern of length at most four. To…

Combinatorics · Mathematics 2021-11-12 Vít Jelínek , Toufik Mansour , José L. Ramírez , Mark Shattuck

Let $\pi \in \mathfrak{S}_m$ and $\sigma \in \mathfrak{S}_n$ be permutations. An occurrence of $\pi$ in $\sigma$ as a consecutive pattern is a subsequence $\sigma_i \sigma_{i+1} \cdots \sigma_{i+m-1}$ of $\sigma$ with the same order…

Combinatorics · Mathematics 2018-07-16 Mitchell Lee , Ashwin Sah

We study questions of even-Wilf-equivalence, the analogue of Wilf-equivalence when attention is restricted to pattern avoidance by permutations in the alternating group. Although some Wilf-equivalence results break when considering…

Combinatorics · Mathematics 2011-06-21 Andrew M. Baxter , Aaron D. Jaggard

We discuss a new notion of pattern avoidance motivated by the operad theory: pattern avoidance in planar labelled trees. It is a generalisation of various types of consecutive pattern avoidance studied before: consecutive patterns in words,…

Combinatorics · Mathematics 2012-01-16 Vladimir Dotsenko

Motivated by a correlation between the distribution of descents over permutations that avoid a consecutive pattern and those avoiding the respective quasi-consecutive pattern, as established in this paper, we obtain a complete $\des$-Wilf…

Combinatorics · Mathematics 2025-02-17 Yan Wang , Qi Fang , Shishuo Fu , Sergey Kitaev , Haijun Li

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 prove a conjecture of Gao and Kitaev on Wilf-equivalence of sets of patterns {12345,12354} and {45123,45213} that extends the list of 10 related conjectures proved in the literature in a series of papers. To achieve our goals, we prove…

Combinatorics · Mathematics 2024-05-24 Alexander Burstein , Tian Han , Sergey Kitaev , Philip Zhang

We say that an unordered rooted labeled forest avoids the pattern $\pi\in\mathcal{S}_n$ if the sequence obtained from the labels along the path from the root to any vertex does not contain a subsequence that is in the same relative order as…

Combinatorics · Mathematics 2017-10-02 Katie Anders , Kassie Archer

Two mesh patterns are coincident if they are avoided by the same set of permutations, and are Wilf-equivalent if they have the same number of avoiders of each length. We provide sufficient conditions for coincidence of mesh patterns, when…

Combinatorics · Mathematics 2023-06-22 Murray Tannock , Henning Ulfarsson

We present two families of Wilf-equivalences for consecutive and quasi-consecutive vincular patterns. These give new proofs of the classification of consecutive patterns of length $4$ and $5$. We then prove additional equivalences to…

Combinatorics · Mathematics 2023-06-22 Evan Chen , Shyam Narayanan

We offer elementary proofs for several results in consecutive pattern containment that were previously demonstrated using ideas from cluster method and analytical combinatorics. Furthermore, we establish new general bounds on the growth…

Combinatorics · Mathematics 2024-05-13 Reza Rastegar

We prove several Wilf-equivalences for vincular patterns of length 4, some of which generalize to infinite families of vincular patterns. We also present functional equations for the generating functions for the number of permutations of…

Combinatorics · Mathematics 2014-08-26 Andrew M. Baxter , Mark Shattuck

Two permutations $\pi$ and $\tau$ are c-Wilf equivalent if, for each $n$, the number of permutations in $S_n$ avoiding $\pi$ as a consecutive pattern (i.e., in adjacent positions) is the same as the number of those avoiding $\tau$. In…

Combinatorics · Mathematics 2018-01-26 Tim Dwyer , Sergi Elizalde

This paper considers the enumeration of trees avoiding a contiguous pattern. We provide an algorithm for computing the generating function that counts n-leaf binary trees avoiding a given binary tree pattern t. Equipped with this counting…

Combinatorics · Mathematics 2015-03-13 Eric S. Rowland

Vincular or dashed patterns resemble classical patterns except that some of the letters within an occurrence are required to be adjacent. We prove several infinite families of Wilf-equivalences for k-ary words involving vincular patterns…

Combinatorics · Mathematics 2014-03-11 Toufik Mansour , Mark Shattuck

We give some new Wilf equivalences for signed patterns which allow the complete classification of signed patterns of lengths three and four. The problem is considered for pattern avoidance by general as well as involutive signed…

Combinatorics · Mathematics 2007-05-23 W. M. B. Dukes , T. Mansour , A. Reifegerste

We extend the notion of shape-Wilf-equivalence to vincular patterns (also known as "generalized patterns" or "dashed patterns"). First we introduce a stronger equivalence on patterns which we call filling-shape-Wilf-equivalence. When…

Combinatorics · Mathematics 2013-02-05 Andrew M. Baxter

In a previous work, B\'ona and Pantone studied permutations that avoided all but one pattern of length $k$ that began with a length $k-1$ increasing subsequence. We draw the connection between that idea and distant patterns, first discussed…

Combinatorics · Mathematics 2025-11-27 Nicholas Van Nimwegen
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