English

Stack-sorting with Stacks Avoiding Vincular Patterns

Combinatorics 2024-10-23 v1

Abstract

We introduce the stack-sorting map SCσ\text{SC}_\sigma that sorts, in a right-greedy manner, an input permutation through a stack that avoids some vincular pattern σ\sigma. The stack-sorting maps of Cerbai et al. in which the stack avoids a pattern classically and Defant and Zheng in which the stack avoids a pattern consecutively follow as special cases. We first characterize and enumerate the sorting class Sort(SCσ)\text{Sort}(\text{SC}_\sigma), the set of permutations sorted by sSCσs\circ\text{SC}_\sigma, for seven length 33 patterns σ\sigma. We also decide when Sort(SCσ)\text{Sort}(\text{SC}_\sigma) is a permutation class. Next, we compute maxπSnSCσ1(π)\max_{\pi\in \mathfrak S_n}|\text{SC}_\sigma^{-1}(\pi)| and characterize the periodic points of SCσ\text{SC}_\sigma for several length 33 patterns σ\sigma. We end with several conjectures and open problems.

Keywords

Cite

@article{arxiv.2410.17057,
  title  = {Stack-sorting with Stacks Avoiding Vincular Patterns},
  author = {William Zhao},
  journal= {arXiv preprint arXiv:2410.17057},
  year   = {2024}
}