English

Pattern avoidance in ordered set partitions and words

Combinatorics 2013-07-02 v1

Abstract

We consider the enumeration of ordered set partitions avoiding a permutation pattern, as introduced by Godbole, Goyt, Herdan and Pudwell. Let \opn,k(p)\op_{n,k}(p) be the number of ordered set partitions of {1,2,,n}\{1,2,\ldots,n\} into kk blocks that avoid a permutation pattern pp. We establish an explicit identity between the number \opn,k(p)\op_{n,k}(p) and the numbers of words avoiding the inverse of pp. This identity allows us to easily translate results on pattern-avoiding words obtained in earlier works into equivalent results on pattern-avoiding ordered set partitions. In particular, \emph{(a)} we determine the asymptotic growth rate of the sequence (\opn,k(p))n1(\op_{n,k}(p))_{n\geq 1} for every positive kk and every permutation pattern pp, \emph{(b)} we partially confirm a conjecture of Godbole et al. concerning the variation of the sequences (\opn,kp))1kn(\op_{n,k}p))_{1\leq k\leq n}, \emph{(c)} we undertake a detailed study of the number of ordered set partitions avoiding a pattern of length 3.

Keywords

Cite

@article{arxiv.1307.0495,
  title  = {Pattern avoidance in ordered set partitions and words},
  author = {Anisse Kasraoui},
  journal= {arXiv preprint arXiv:1307.0495},
  year   = {2013}
}
R2 v1 2026-06-22T00:43:48.568Z