English

On two conjectures about pattern avoidance of cyclic permutations

Combinatorics 2025-05-06 v1

Abstract

Let π\pi be a cyclic permutation that can be expressed in its one-line form as π=π1π2πn\pi = \pi_1\pi_2 \cdot\cdot\cdot \pi_n and in its standard cycle form as π=(c1,c2,...,cn)\pi = (c_1,c_2, ..., c_n) where c1=1c_1=1. Archer et al. introduced the notion of pattern avoidance of one-line and the standard cycle form for a cyclic permutation π\pi, defined as both π1π2πn\pi_1\pi_2 \cdot\cdot\cdot \pi_n and its standard cycle form c1c2cnc_1c_2\cdot\cdot\cdot c_{n} avoiding a given pattern. Let An(σ1,...,σk;τ)\mathcal{A}_n(\sigma_1,...,\sigma_k; \tau) denote the set of cyclic permutations in the symmetric group SnS_n that avoid each pattern of {σ1,...,σk}\{\sigma_1,...,\sigma_k\} in their one-line forms and avoid τ\tau in their standard cycle forms. In this paper, we obtain some results about the cyclic permutations avoiding patterns in both one-line and cycle forms. In particular, we resolve two conjectures of Archer et al.

Keywords

Cite

@article{arxiv.2505.02045,
  title  = {On two conjectures about pattern avoidance of cyclic permutations},
  author = {Junyao Pan},
  journal= {arXiv preprint arXiv:2505.02045},
  year   = {2025}
}
R2 v1 2026-06-28T23:20:31.748Z