Results 1 to 10 of about 143 (87)
Some equinumerous pattern-avoiding classes of permutations [PDF]
Discrete Mathematics & Theoretical Computer Science, 2005 Suppose that p,q,r,s are non-negative integers with m=p+q+r+s. The class X(p,q,r,s) of permutations that contain no pattern of the form αβγ where |α|=r, |γ|=s and β is any arrangement of {1,2,…,p}∪{m-q+1, m-q+2, …,m} is considered.
M. D. Atkinson
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Antipowers in Uniform Morphic Words and the Fibonacci Word [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 Fici, Restivo, Silva, and Zamboni define a $k$-antipower to be a word composed of $k$ pairwise distinct, concatenated words of equal length. Berger and Defant conjecture that for any sufficiently well-behaved aperiodic morphic word $w$, there exists a ...
Swapnil Garg
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Further enumeration results concerning a recent equivalence of restricted inversion sequences [PDF]
Discrete Mathematics & Theoretical Computer Science, 2022 Let asc and desc denote respectively the statistics recording the number of ascents or descents in a sequence having non-negative integer entries.
Toufik Mansour, Mark Shattuck
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Positional Marked Patterns in Permutations [PDF]
Discrete Mathematics & Theoretical Computer Science, 2022 We define and study positional marked patterns, permutations $\tau$ where one of elements in $\tau$ is underlined. Given a permutation $\sigma$, we say that $\sigma$ has a $\tau$-match at position $i$ if $\tau$ occurs in $\sigma$ in such a way that ...
Sittipong Thamrongpairoj +1 more
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Recent developments in combinatorial aspects of normal ordering
Enumerative Combinatorics and Applications, 2021 In this paper, we report on recent progress concerning combinatorial aspects of normal ordering. After giving a short introduction to the history and motivation of normal ordering, we present some recent developments.
M. Schork
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A Bijection on Classes Enumerated by the Schröder Numbers [PDF]
Discrete Mathematics & Theoretical Computer Science, 2017 We consider a sorting machine consisting of two stacks in series where the first stack has the added restriction that entries in the stack must be in decreasing order from top to bottom.
Michael W. Schroeder, Rebecca Smith
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Anti-power $j$-fixes of the Thue-Morse word [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 Recently, Fici, Restivo, Silva, and Zamboni introduced the notion of a $k$-anti-power, which is defined as a word of the form $w^{(1)} w^{(2)} \cdots w^{(k)}$, where $w^{(1)}, w^{(2)}, \ldots, w^{(k)}$ are distinct words of the same length.
Marisa Gaetz
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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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Enumeration of weighted paths on a digraph and block hook determinant
Special Matrices, 2021 In this article, we evaluate determinants of “block hook” matrices, which are block matrices consist of hook matrices. In particular, we deduce that the determinant of a block hook matrix factorizes nicely.
Bera Sudip
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Two examples of Wilf-collapse [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 Two permutation classes, the X-class and subpermutations of the increasing oscillation are shown to exhibit an exponential Wilf-collapse. This means that the number of distinct enumerations of principal subclasses of each of these classes grows much more
Michael Albert +2 more
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