Wilf Classes of Pairs of Permutations of Length 4
نویسنده
چکیده
Sn(π1, π2, . . . , πr) denotes the set of permutations of length n that have no subsequence with the same order relations as any of the πi. In this paper we show that |Sn(1342, 2143)| = |Sn(3142, 2341)| and |Sn(1342, 3124)| = |Sn(1243, 2134)|. These two facts complete the classification of Wilf-equivalence classes for pairs of permutations of length four. In both instances we exhibit bijections between the sets using the idea of a “block”, and in the former we find a generating function for |Sn(1342, 2143)|.
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ورودعنوان ژورنال:
- Electr. J. Comb.
دوره 12 شماره
صفحات -
تاریخ انتشار 2005