Pattern frequency sequences and internal zeros
组合数学
2007-05-23 v1
摘要
Consider the number of permutations in the symmetric group on n letters that contain c copies of a given pattern. As c varies (with n held fixed) these numbers form a sequence whose properties we study for the monotone patterns and the patterns 1, l, l-1, ..., 2. We show that, except for the patterns 1, 2 and 2, 1 where the sequence is well-known to be log concave, there are infinitely many n where the sequence has internal zeros.
引用
@article{arxiv.math/0104098,
title = {Pattern frequency sequences and internal zeros},
author = {Miklos Bona and Bruce Sagan and Vincent Vatter},
journal= {arXiv preprint arXiv:math/0104098},
year = {2007}
}
备注
24 pages