Results 31 to 40 of about 114,014 (293)
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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European Journal of Combinatorics, 2001 Recently, Babson and Steingrimsson have introduced generalised permutation patterns that allow the requirement that two adjacent letters in a pattern must be adjacent in the permutation. We consider pattern avoidance for such patterns, and give a complete solution for the number of permutations avoiding any single pattern of length three with exactly ...
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Coincidental pattern avoidance [PDF]
Journal of Combinatorics, 2013 There are several versions of permutation pattern avoidance that have arisen in the literature, and some known examples of two different types of pattern avoidance coinciding. In this paper, we examine barred patterns and vincular patterns. Answering a question of Steingrimsson, we determine when barred pattern avoidance coincides with avoiding a ...
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Permutation Pattern matching in (213, 231)-avoiding permutations [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 Given permutations σ of size k and π of size n with k < n, the permutation pattern matching problem is to decide whether σ occurs in π as an order-isomorphic subsequence.
Both Neou +2 more
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Advances in Applied Mathematics, 2012 We extend the notion of consecutive pattern avoidance to considering sums over all permutations where each term is a product of weights depending on each consecutive pattern of a fixed length. We study the problem of finding the asymptotics of these sums. Our technique is to extend the spectral method of Ehrenborg, Kitaev and Perry.
Ehrenborg, Richard, Jung, Jiyoon
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Pattern Avoidance Classes and Subpermutations [PDF]
The Electronic Journal of Combinatorics, 2005 Pattern avoidance classes of permutations that cannot be expressed as unions of proper subclasses can be described as the set of subpermutations of a single bijection. In the case that this bijection is a permutation of the natural numbers a structure theorem is given.
Atkinson, M. D. +2 more
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On avoidance of patterns of the form σ-τ by words over a finite alphabet [PDF]
Discrete Mathematics & Theoretical Computer Science, 2015 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 containing a ...
Toufik Mansour, Mark Shattuck
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Pattern Avoidance by Even Permutations [PDF]
The Electronic Journal of Combinatorics, 2011 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 even-Wilf-equivalence analogues, we prove that other Wilf-equivalence results continue to hold in the even-Wilf ...
Baxter, Andrew, Jaggard, Aaron D.
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Wilf classification of triples of 4-letter patterns II [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 this is the second part of a complete paper in arXiv, see 1605 ...
David Callan +2 more
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