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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 classical notion of permutation patterns within the framework of pattern avoidance. Building on recent work by Burstein, Han, Kitaev, and Zhang, which introduced the concept of…

Combinatorics · Mathematics 2025-10-22 Sucharita Biswas , Umesh Shankar , Sivaramakrishnan Sivasubramanian

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 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 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 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

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

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

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

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

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

An occurrence of a classical pattern p in a permutation \pi is a subsequence of \pi whose letters are in the same relative order (of size) as those in p. In an occurrence of a generalized pattern, some letters of that subsequence may be…

Combinatorics · Mathematics 2008-05-31 Einar Steingrimsson

Flip-sort is a natural sorting procedure which raises fascinating combinatorial questions. It finds its roots in the seminal work of Knuth on stack-based sorting algorithms and leads to many links with permutation patterns. We present…

Combinatorics · Mathematics 2023-06-22 Andrei Asinowski , Cyril Banderier , Benjamin Hackl

The Rearrangement Conjecture states that if two words over $\mathbb{P}$ are Wilf-equivalent in the factor order on $\mathbb{P}^\ast$ then they are rearrangements of each other. We introduce the notion of strong Wilf-equivalence and prove…

Combinatorics · Mathematics 2014-09-15 Jay Pantone , Vincent Vatter

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

A quotient of a poset $P$ is a partial order obtained on the equivalence classes of an equivalence relation $\theta$ on $P$; $\theta$ is then called a congruence if it satisfies certain conditions, which vary according to different…

Combinatorics · Mathematics 2025-08-20 Nicholas J. Williams

We study the partially ordered set of equivalence classes of quantum measurements endowed with the post-processing partial order. The post-processing order is fundamental as it enables to compare measurements by their intrinsic noise and it…

Quantum Physics · Physics 2022-11-14 Teiko Heinosaari , Maria Anastasia Jivulescu , Ion Nechita

The aim of the present paper is to investigate the half-spaces in the convexity structure of all quasiorders on a given set and to use them in an alternative approach to classical order dimension. The main result states that linear orders…

Combinatorics · Mathematics 2009-02-17 Stephan Foldes , Jeno Szigeti
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