English

Descent set distribution for permutations with cycles of only odd or only even lengths

Combinatorics 2025-02-07 v1

Abstract

It is known that the number of permutations in the symmetric group S2nS_{2n} with cycles of odd lengths only is equal to the number of permutations with cycles of even lengths only. We prove a refinement of this equality, involving descent sets: the number of permutations in S2nS_{2n} with a prescribed descent set and all cycles of odd lengths is equal to the number of permutations with the complementary descent set and all cycles of even lengths. There is also a variant for S2n+1S_{2n+1}. The proof uses generating functions for character values and applies a new identity on higher Lie characters.

Keywords

Cite

@article{arxiv.2502.03507,
  title  = {Descent set distribution for permutations with cycles of only odd or only even lengths},
  author = {Ron M. Adin and Pál Hegedűs and Yuval Roichman},
  journal= {arXiv preprint arXiv:2502.03507},
  year   = {2025}
}

Comments

23 pages. arXiv admin note: substantial text overlap with arXiv:2312.08904