Longest alternating subsequences of permutations
组合数学
2007-05-23 v1
摘要
The length is(w) of the longest increasing subsequence of a permutation w in the symmetric group S_n has been the object of much investigation. We develop comparable results for the length as(w) of the longest alternating subsequence of w, where a sequence a,b,c,d,... is alternating if a>b<c>d<.... For instance, the expected value (mean) of as(w) for w in S_n is exactly (4n+1)/6 if n>1.
关键词
引用
@article{arxiv.math/0511419,
title = {Longest alternating subsequences of permutations},
author = {Richard P. Stanley},
journal= {arXiv preprint arXiv:math/0511419},
year = {2007}
}
备注
19 pages