Even Signed Permutations Avoiding 2-Letter Signed Patterns |
Received:December 27, 2007 Revised:February 28, 2008 |
Key Words:
forbidden pattern signed permutation Catalan number.
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Fund Project:the National Natural Science Foundation of China (No.10801020). |
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Abstract: |
Let ${\cal D}_n$ be the set of all signed permutations on $[n]=\{1,\dots, n\}$ with even signs, and let ${\cal D}_n(T)$ be the set of all signed permutations in ${\cal D}_n$ which avoids a set $T$ of signed patterns. In this paper, we find all the cardinalities of the sets ${\cal D}_n(T)$ where $T\subseteq B_2$. Some of the cardinalities encountered involve inverse binomial coefficients, binomial coefficients, Catalan numbers, and Fibonacci numbers. |
Citation: |
DOI:10.3770/j.issn:1000-341X.2009.05.006 |
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