English

On a question about pattern avoidance of cyclic permutations

Combinatorics 2026-03-09 v1

Abstract

Recently, Archer et al.\ studied cyclic permutations that avoid the decreasing pattern δk=k(k1)21\delta_k=k(k-1)\cdots21 in one-line notation and avoid another pattern τ\tau of length 44 in all their cycle forms. There are three cases in total to consider, namely, τ=1324,1342\tau=1324, 1342 and 14321432. They determined two of them, leaving the case τ=1432\tau=1432 as an open question. In this paper, we resolve this case by deriving explicit formulas based on an analysis of the structure of cycle forms and an application of Dilworth's theorem.

Keywords

Cite

@article{arxiv.2603.06269,
  title  = {On a question about pattern avoidance of cyclic permutations},
  author = {Zuo-Ru Zhang and Hongkuan Zhao},
  journal= {arXiv preprint arXiv:2603.06269},
  year   = {2026}
}

Comments

12 pages

R2 v1 2026-07-01T11:06:50.016Z