English

A central limit theorem for cycles of Mallows permutations

Probability 2022-06-22 v4 Combinatorics

Abstract

Fix q1q\neq 1, and sample wSnw\in S_n from the Mallows measure. We study the distribution of Ci(w)C_i(w), the number of ii-cycles, as nn grows large. When q<1q<1, they are jointly Gaussian, and this more or less follows from known ideas, but the regime q>1q>1 behaves quite differently. In particular, we show that the even cycles C2i(w)C_{2i}(w) have a mean and variance of order nn, and jointly converge to Gaussian random variables, while the odd cycles C2i+1(w)C_{2i+1}(w) have a bounded mean and variance, and converge to C2i+1(weven)C_{2i+1}(w^{even}) or C2i+1(wodd)C_{2i+1}(w^{odd}) for some explicit random permutations wevenw^{even} and woddw^{odd}, depending on whether nn is even or odd. An extension to a larger class of functions is also given. The proof utilizes a two-sided stationary regenerative process associated to Mallows permutations constructed by Gnedin and Olshanski, extending the ideas of Basu and Bhatnagar.

Keywords

Cite

@article{arxiv.2112.09789,
  title  = {A central limit theorem for cycles of Mallows permutations},
  author = {Jimmy He},
  journal= {arXiv preprint arXiv:2112.09789},
  year   = {2022}
}

Comments

This paper has been merged with arXiv:2201.11610

R2 v1 2026-06-24T08:22:42.581Z