English

Continued fractions for permutation statistics

Combinatorics 2023-06-22 v4

Abstract

We explore a bijection between permutations and colored Motzkin paths that has been used in different forms by Foata and Zeilberger, Biane, and Corteel. By giving a visual representation of this bijection in terms of so-called cycle diagrams, we find simple translations of some statistics on permutations (and subsets of permutations) into statistics on colored Motzkin paths, which are amenable to the use of continued fractions. We obtain new enumeration formulas for subsets of permutations with respect to fixed points, excedances, double excedances, cycles, and inversions. In particular, we prove that cyclic permutations whose excedances are increasing are counted by the Bell numbers.

Keywords

Cite

@article{arxiv.1703.08742,
  title  = {Continued fractions for permutation statistics},
  author = {Sergi Elizalde},
  journal= {arXiv preprint arXiv:1703.08742},
  year   = {2023}
}

Comments

final version formatted for DMTCS

R2 v1 2026-06-22T18:56:55.116Z