Parities in random Latin squares

Fuente: arXiv
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Main Authors: Kwan, Matthew, Petrova, Kalina, Sawhney, Mehtaab
Format: Preprint
Published: 2025
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author Kwan, Matthew
Petrova, Kalina
Sawhney, Mehtaab
author_facet Kwan, Matthew
Petrova, Kalina
Sawhney, Mehtaab
contents 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 $n\times n$ Latin square, the $n$ row parities are very well approximated by a sequence of $n$ independent unbiased coin flips: for example, the total variation error of this approximation tends to zero as $n\to\infty$. 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.
format Preprint
id arxiv_https___arxiv_org_abs_2509_13125
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Parities in random Latin squares
Kwan, Matthew
Petrova, Kalina
Sawhney, Mehtaab
Probability
Combinatorics
05B15, 05C80, 60B99, 05C65
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 $n\times n$ Latin square, the $n$ row parities are very well approximated by a sequence of $n$ independent unbiased coin flips: for example, the total variation error of this approximation tends to zero as $n\to\infty$. 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.
title Parities in random Latin squares
topic Probability
Combinatorics
05B15, 05C80, 60B99, 05C65
url https://arxiv.org/abs/2509.13125