Kassie Archer ; Noel Bourne - Pattern avoidance in compositions and powers of permutations

dmtcs:17199 - Discrete Mathematics & Theoretical Computer Science, May 19, 2026, vol. 28:1, Permutation Patterns 2025 - https://doi.org/10.46298/dmtcs.17199
Pattern avoidance in compositions and powers of permutationsArticle

Authors: Kassie Archer ; Noel Bourne

A permutation $π$ is said to avoid a chain $(σ:τ)$ of patterns if $π$ avoids $σ$ and $π^2$ avoids $τ.$ In this paper, we define a notion of pattern avoidance for compositions of positive integers and use that idea to enumerate permutations of length $n$ that avoid the chain $(312,321:σ)$ for any pattern $σ\in \bigcup_{m\geq 1} S_m$. We also enumerate those permutations that avoid the chain $(312,4321:σ)$ for any $σ\in S_3.$


Volume: vol. 28:1, Permutation Patterns 2025
Section: Special issues
Published on: May 19, 2026
Accepted on: May 4, 2026
Submitted on: December 28, 2025
Keywords: Combinatorics