English

A bijection between $321$- and $213$-avoiding permutations preserving $t$-stack-sortability

Combinatorics 2025-07-15 v1

Abstract

We construct a bijection between 321321- and 213213-avoiding permutations that preserves the property of tt-stack-sortability. Our bijection transforms natural statistics between these two classes of permutations and proves a refinement of an enumerative conjecture posed by Zhang and Kitaev. This work contributes further to the long-standing line of research on bijections between length-3 pattern avoiding permutations. Increasing binary trees lie at the heart of our approach.

Keywords

Cite

@article{arxiv.2507.09187,
  title  = {A bijection between $321$- and $213$-avoiding permutations preserving $t$-stack-sortability},
  author = {Yang Li and Sergey Kitaev and Zhicong Lin and Jing Liu},
  journal= {arXiv preprint arXiv:2507.09187},
  year   = {2025}
}

Comments

16 pages, 7 figures

R2 v1 2026-07-01T03:57:46.134Z