Results 21 to 30 of about 114,014 (293)
Alternating, Pattern-Avoiding Permutations [PDF]
The Electronic Journal of Combinatorics, 2009 We study the problem of counting alternating permutations avoiding collections of permutation patterns including $132$. We construct a bijection between the set $S_n(132)$ of $132$-avoiding permutations and the set $A_{2n + 1}(132)$ of alternating, $132$-avoiding permutations. For every set $p_1, \ldots, p_k$ of patterns and certain related patterns $
openaire +3 more sources
Permutations Avoiding Certain Partially-Ordered Patterns [PDF]
The Electronic Journal of Combinatorics, 2021 A permutation $\pi$ contains a pattern $\sigma$ if and only if there is a subsequence in $\pi$ with its letters in the same relative order as those in $\sigma$. Partially ordered patterns (POPs) provide a convenient way to denote patterns in which the relative order of some of the letters does not matter.
Yap, Kai Ting Keshia +2 more
openaire +3 more sources
Crucial abelian k-power-free words [PDF]
Discrete Mathematics & Theoretical Computer Science, 2010 Combinatorics
Amy Glen +2 more
doaj +1 more source
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
doaj +1 more source
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
openaire +2 more sources
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?
openaire +2 more sources
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
openaire +3 more sources
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
doaj +1 more source
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
openaire +2 more sources
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.
openaire +2 more sources