English

A note on the total number of cycles of even and odd permutations

Combinatorics 2010-04-07 v2

Abstract

We prove bijectively that the total number of cycles of all even permutations of [n]={1,2,...,n}[n]=\{1,2,...,n\} and the total number of cycles of all odd permutations of [n][n] differ by (1)n(n2)!(-1)^n(n-2)!, which was stated as an open problem by Mikl\'{o}s B\'{o}na. We also prove bijectively the following more general identity: i=1nc(n,i)i(k)i1=(1)kk!(nk1)!,\sum_{i=1}^n c(n,i)\cdot i \cdot (-k)^{i-1} = (-1)^k k! (n-k-1)!, where c(n,i)c(n,i) denotes the number of permutations of [n][n] with ii cycles.

Keywords

Cite

@article{arxiv.0909.0683,
  title  = {A note on the total number of cycles of even and odd permutations},
  author = {Jang Soo Kim},
  journal= {arXiv preprint arXiv:0909.0683},
  year   = {2010}
}

Comments

4 pages, 2 figures, final version