منابع مشابه
Refined Restricted Permutations
Define Sk n(α) to be the set of permutations of {1, 2, . . . ,n} with exactly k fixed points which avoid the pattern α∈ Sm. Let sn(α) be the size of Sk n(α). We investigate S0 n(α) for all α∈ S3 as well as show that sn(132) = s k n(213) = s k n(321) and s k n(231) = s k n(312) for all 0 ≤ k ≤ n.
متن کاملBijections for refined restricted permutations
We present a bijection between 321and 132-avoiding permutations that preserves the number of fixed points and the number of excedances. This gives a simple combinatorial proof of recent results of Robertson et al. (Ann. Combin. 6 (2003) 427), and Elizalde (Proc. FPSAC 2003). We also show that our bijection preserves additional statistics, which extends the
متن کاملBijections for Refined Restricted Permutations Sergi Elizalde and Igor Pak
We present a bijection between 321and 132-avoiding permutations that preserves the number of fixed points and the number of excedances. This gives a simple combinatorial proof of recent results of Robertson, Saracino and Zeilberger [8], and the first author [3]. We also show that our bijection preserves additional statistics, which extends the previous results.
متن کاملRefined Restricted Permutations Avoiding Subsets of Patterns of Length Three
Define Sk n(T ) to be the set of permutations of {1, 2, . . . , n} with exactly k fixed points which avoid all patterns in T ⊆ Sm. We enumerate Sk n(T ), T ⊆ S3, for all |T | ≥ 2 and 0 ≤ k ≤ n.
متن کاملRestricted permutations
Restricted permutations are those constrained by having to avoid subsequences ordered in various prescribed ways. They have functioned as a convenient descriptor for several sets of permutations which arise naturally in combinatorics and computer science. We study the partial order on permutations (and more general sequences) that underlies the idea of restriction and which gives rise to sets o...
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ژورنال
عنوان ژورنال: Annals of Combinatorics
سال: 2002
ISSN: 0218-0006,0219-3094
DOI: 10.1007/s000260200015