Results 1 to 10 of about 99 (75)
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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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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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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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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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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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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Enumeration of Stack-Sorting Preimages via a Decomposition Lemma [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 We give three applications of a recently-proven "Decomposition Lemma," which allows one to count preimages of certain sets of permutations under West's stack-sorting map $s$.
Colin Defant
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Enumeration of Dumont permutations avoiding certain four-letter patterns [PDF]
Discrete Mathematics & Theoretical Computer Science, 2021 In this paper, we enumerate Dumont permutations of the fourth kind avoiding or containing certain permutations of length 4. We also conjecture a Wilf-equivalence of two 4-letter patterns on Dumont permutations of the first kind.
Alexander Burstein, Opel Jones
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Cyclic permutations avoiding pairs of patterns of length three [PDF]
Discrete Mathematics & Theoretical Computer Science, 2019 We complete the enumeration of cyclic permutations avoiding two patterns of length three each by providing explicit formulas for all but one of the pairs for which no such formulas were known. The pair $(123,231)$ proves to be the most difficult of these
Miklos Bona, Michael Cory
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