English

Parities in random Latin squares

Probability 2025-09-19 v2 Combinatorics

Abstract

In a Latin square, every row can be interpreted as a permutation, and therefore has a parity (even or odd). We prove that in a uniformly random n×nn\times n Latin square, the nn row parities are very well approximated by a sequence of nn independent unbiased coin flips: for example, the total variation error of this approximation tends to zero as nn\to\infty. This resolves a conjecture of Cameron. In fact, we prove a generalisation of Cameron's conjecture for the joint distribution of the row parities, column parities and symbol parities (the latter are defined by the symmetry between rows, columns and symbols of a Latin square). Along the way, we introduce several general techniques for the study of random Latin squares, including a new re-randomisation technique via `stable intercalate switchings', and a new approximation theorem comparing random Latin squares with a certain independent model.

Keywords

Cite

@article{arxiv.2509.13125,
  title  = {Parities in random Latin squares},
  author = {Matthew Kwan and Kalina Petrova and Mehtaab Sawhney},
  journal= {arXiv preprint arXiv:2509.13125},
  year   = {2025}
}

Comments

The previous version had a bug related to clever references that appears only on arxiv, causing all theorem-type statements to be referenced as theorems. This new version fixes that bug

R2 v1 2026-07-01T05:39:32.441Z