# Stack words and a bound for 3-stack sortable permutations

## TL;DR

This paper introduces a novel approach using stack words to provide a simple proof for the upper bound on the number of 3-stack sortable permutations, marking a first in applying this method for such results.

## Contribution

The paper presents the first use of stack words to derive an upper bound for 3-stack sortable permutations, offering a new proof technique.

## Key findings

- Established a new upper bound for 3-stack sortable permutations
- Provided the first proof using stack words for this bound
- Simplified the understanding of permutation sorting complexity

## Abstract

We use stack words to find a new, simple proof for the best known upper bound for the number of 3-stack sortable permutations of a given length. This is the first time that stack words are used to obtain such a result.