English

Right-jumps and pattern avoiding permutations

Discrete Mathematics 2023-06-22 v5 Combinatorics Probability

Abstract

We study the iteration of the process "a particle jumps to the right" in permutations. We prove that the set of permutations obtained in this model after a given number of iterations from the identity is a class of pattern avoiding permutations. We characterize the elements of the basis of this class and we enumerate these "forbidden minimal patterns" by giving their bivariate exponential generating function: we achieve this via a catalytic variable, the number of left-to-right maxima. We show that this generating function is a D-finite function satisfying a nice differential equation of order~2. We give some congruence properties for the coefficients of this generating function, and we show that their asymptotics involves a rather unusual algebraic exponent (the golden ratio (1+5)/2(1+\sqrt 5)/2) and some unusual closed-form constants. We end by proving a limit law: a forbidden pattern of length nn has typically (lnn)/5(\ln n) /\sqrt{5} left-to-right maxima, with Gaussian fluctuations.

Cite

@article{arxiv.1512.02171,
  title  = {Right-jumps and pattern avoiding permutations},
  author = {Cyril Banderier and Jean-Luc Baril and Céline Moreira Dos Santos},
  journal= {arXiv preprint arXiv:1512.02171},
  year   = {2023}
}

Comments

Following the work presented at the conferences Analysis of Algorithms (AofA'15) and Permutation Patterns'15, this arXiv version corresponds to the version published in DMTCS, up to minor details/typos fixed here

R2 v1 2026-06-22T12:03:32.192Z