Results 21 to 30 of about 116,248 (268)
Wilf classification of triples of 4-letter patterns I [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 This paper is first part of a complete paper in arXiv , see 1605.04969.
David Callan +2 more
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Grasshopper Avoidance of Patterns
The Electronic Journal of Combinatorics, 2016 Motivated by a geometrical Thue-type problem, we introduce a new variant of the classical pattern avoidance in words, where jumping over a letter in the pattern occurrence is allowed. We say that pattern $p\in E^+$ occurs with jumps in a word $w=a_1a_2\ldots a_k \in A^+$, if there exist a non-erasing morphism $f$ from $E^*$ to $A^*$ and a sequence ...
Dębski, Michał +2 more
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Permutations Avoiding Arithmetic Patterns [PDF]
The Electronic Journal of Combinatorics, 2004 A permutation $\pi$ of an abelian group $G$ (that is, a bijection from $G$ to itself) will be said to avoid arithmetic progressions if there does not exist any triple $(a,b,c)$ of elements of $G$, not all equal, such that $c-b=b-a$ and $\pi(c)-\pi(b)=\pi(b)- \pi(a)$. The basic question is, which abelian groups possess such a permutation?
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Pattern Avoidance in Ascent Sequences [PDF]
The Electronic Journal of Combinatorics, 2011 Ascent sequences are sequences of nonnegative integers with restrictions on the size of each letter, depending on the number of ascents preceding it in the sequence. Ascent sequences have recently been related to $(2+2)$-free posets and various other combinatorial structures.
Duncan, Paul, Steingrimsson, Einar
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Bounded affine permutations I. Pattern avoidance and enumeration [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 We introduce a new boundedness condition for affine permutations, motivated by the fruitful concept of periodic boundary conditions in statistical physics. We study pattern avoidance in bounded affine permutations.
Neal Madras, Justin M. Troyka
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Pattern Avoidance in Reverse Double Lists [PDF]
Discrete Mathematics & Theoretical Computer Science, 2018 In this paper, we consider pattern avoidance in a subset of words on $\{1,1,2,2,\dots,n,n\}$ called reverse double lists. In particular a reverse double list is a word formed by concatenating a permutation with its reversal.
Monica Anderson +3 more
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Pattern avoidance of generalized permutations [PDF]
Advances in Applied Mathematics, 2019 In this paper, we study pattern avoidances of generalized permutations and show that the number of all generalized permutations avoiding $π$ is independent of the choice of $π\in S_3$, which extends the classic results on permutations avoiding $π\in S_3$.
Mei, Zhousheng, Wang, Suijie
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On Pattern-Avoiding Fishburn Permutations [PDF]
Annals of Combinatorics, 2019 The class of permutations that avoid the bivincular pattern (231, {1},{1}) is known to be enumerated by the Fishburn numbers. In this paper, we call them Fishburn permutations and study their pattern avoidance. For classical patterns of size 3, we give a complete enumerative picture for regular and indecomposable Fishburn permutations.
Gil, Juan B., Weiner, Michael D.
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Doubled Patterns are 3-Avoidable [PDF]
The Electronic Journal of Combinatorics, 2016 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 $f$ of $w$ such that $f=h(p)$ where $h: \Delta^*\to\Sigma^*$ is a non-erasing morphism. A pattern $p$ is said to be $k$-avoidable if there exists an infinite word over a $k$-letter alphabet that avoids $p$.
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Patterns in matchings and rook placements [PDF]
Discrete Mathematics & Theoretical Computer Science, 2013 Extending the notion of pattern avoidance in permutations, we study matchings and set partitions whose arc diagram representation avoids a given configuration of three arcs.
Jonathan Bloom, Sergi Elizalde
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