Pattern avoidance in ordered set partitions and words
Abstract
We consider the enumeration of ordered set partitions avoiding a permutation pattern, as introduced by Godbole, Goyt, Herdan and Pudwell. Let be the number of ordered set partitions of into blocks that avoid a permutation pattern . We establish an explicit identity between the number and the numbers of words avoiding the inverse of . 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 for every positive and every permutation pattern , \emph{(b)} we partially confirm a conjecture of Godbole et al. concerning the variation of the sequences , \emph{(c)} we undertake a detailed study of the number of ordered set partitions avoiding a pattern of length 3.
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}
}