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A partially ordered pattern (abbreviated POP) is a partially ordered set (poset) that generalizes the notion of a pattern when we are not concerned with the relative order of some of its letters. The notion of partially ordered patterns…

Combinatorics · Mathematics 2025-07-17 Lintong Wang , Sherry H. F. Yan

Partially ordered patterns (POPs) generalize the notion of classical patterns studied in the literature in the context of permutations, words, compositions and partitions. In this paper, we give a number of general, and specific enumerative…

Combinatorics · Mathematics 2022-04-20 Sergey Kitaev , Artem Pyatkin

Partially ordered patterns (POPs) generalize classical permutation patterns and have been extensively studied in the contexts of permutations, words, compositions, and partitions. Burstein, Han, Kitaev, and Zhang established the…

Combinatorics · Mathematics 2026-05-01 Sucharita Biswas

Partially ordered patterns (POPs) generalize the notion of classical patterns studied widely in the literature in the context of permutations, words, compositions and partitions. In an occurrence of a POP, the relative order of some of the…

Combinatorics · Mathematics 2019-03-22 Alice L. L. Gao , Sergey Kitaev

A partially ordered (generalized) pattern (POP) is a generalized pattern some of whose letters are incomparable, an extension of generalized permutation patterns introduced by Babson and Steingrimsson. POPs were introduced in the symmetric…

Combinatorics · Mathematics 2007-05-23 Silvia Heubach , Sergey Kitaev , Toufik Mansour

A permutation $\pi$ contains a pattern $\sigma$ if and only if there is a subsequence in $\pi$ with its letters are in the same relative order as those in $\sigma$. Partially ordered patterns (POPs) provide a convenient way to denote…

Combinatorics · Mathematics 2021-01-29 Kai Ting Keshia Yap , David Wehlau , Imed Zaguia

We review selected known results on partially ordered patterns (POPs) that include co-unimodal, multi- and shuffle patterns, peaks and valleys ((modified) maxima and minima) in permutations, the Horse permutations and others. We provide…

Combinatorics · Mathematics 2007-05-23 Sergey Kitaev

Partially ordered patterns (POPs) play an important role in the study of permutation patterns, providing a convenient framework for describing large families of classical patterns. The problem of enumerating permutations that avoid POPs has…

Combinatorics · Mathematics 2026-03-05 Shiqi Cao , Huihua Gao , Sergey Kitaev , Yitian Li

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

Finding distributions of statistics in pattern-avoiding permutations has attracted significant attention in the literature. In particular, Chen, Kitaev, and Zhang derived functional equations for the joint distributions of any subset of…

Combinatorics · Mathematics 2025-09-19 Alice L. L. Gao , Sergey Kitaev , Ya-Xing Li , Xuan Ruan

We prove that any class of permutations defined by avoiding a partially ordered pattern (POP) with height at most two has a regular insertion encoding and thus has a rational generating function. Then, we use Combinatorial Exploration to…

Combinatorics · Mathematics 2023-12-14 Christian Bean , Émile Nadeau , Jay Pantone , Henning Ulfarsson

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

Let $W$ be an irreducible Coxeter group. We define the Coxeter pop-stack-sorting operator $\mathsf{Pop}:W\to W$ to be the map that fixes the identity element and sends each nonidentity element $w$ to the meet of the elements covered by $w$…

Combinatorics · Mathematics 2022-09-07 Colin Defant

Recently, Kitaev [Ki2] introduced partially ordered generalized patterns (POGPs) in the symmetric group, which further generalize the generalized permutation patterns introduced by Babson and Steingr\'imsson [BS]. A POGP p is a GP some of…

Combinatorics · Mathematics 2007-05-23 S. Kitaev , T. Mansour

We extend the concept of pattern avoidance in permutations on a totally ordered set to pattern avoidance in permutations on partially ordered sets. The number of permutations on $P$ that avoid the pattern $\pi$ is denoted $Av_P(\pi)$. We…

Combinatorics · Mathematics 2019-12-24 Sam Hopkins , Morgan Weiler

The research on pattern-avoidance has yielded so far limited knowledge on Wilf-ordering of permutations. The Stanley-Wilf limits sqrt[n](|S_n(tau)|) and further works suggest asymptotic ordering of layered versus monotone patterns. Yet,…

Combinatorics · Mathematics 2009-09-29 Zvezdelina Stankova

In this undergraduate thesis, we expand on the study of statistics on restricted growth functions avoiding patterns initiated by Campbell, et. al. Restricted growth functions are of interest because they are in bijection with set…

Combinatorics · Mathematics 2020-03-12 Robert Dorward

We present a method of computing the generating function $f_P(\x)$ of $P$-partitions of a poset $P$. The idea is to introduce two kinds of transformations on posets and compute $f_P(\x)$ by recursively applying these transformations. As an…

Combinatorics · Mathematics 2014-11-26 Daniel K. Du , Qing-Hu Hou

In this paper, we first show that for a countable family of random elements taking values in a partially ordered Polish space (POP), association (both positive and negative) of all finite dimensional marginals implies that of the infinite…

Probability · Mathematics 2019-12-04 Guenter Last , Ryszard Szekli , D. Yogeshwaran

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
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