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arXiv:math/0212221 [math.CO]AbstractReferencesReviewsResources

Fixed points and excedances in restricted permutations

Sergi Elizalde

Published 2002-12-16Version 1

In this paper we prove that among the permutations of length n with i fixed points and j excedances, the number of 321-avoiding ones equals the number of 132-avoiding ones, for all given i,j<=n. We use a new technique involving diagonals of non-rational generating functions. This theorem generalizes a recent result of Robertson, Saracino and Zeilberger, for which we also give another, more direct proof.

Comments: 12 pages, 10 figures, submitted to FPSAC'03
Categories: math.CO
Subjects: 05A15
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