Rates of convergence for extremal spacings in Kakutani's random interval-splitting process

Fuente: arXiv
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Main Authors: Daly, Fraser, Wade, Andrew
Format: Preprint
Published: 2025
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author Daly, Fraser
Wade, Andrew
author_facet Daly, Fraser
Wade, Andrew
contents Kakutani's random interval-splitting process iteratively divides, via a uniformly random splitting point, the largest sub-interval in a partition of the unit interval. The length of the longest sub-interval after $n$ steps, suitably centred and scaled, is known to satisfy a central limit theorem as $n \to \infty$. We provide a quantitative (Berry-Esseen) upper bound for the finite-$n$ approximation in the central limit theorem, with conjecturally optimal rates in $n$. We also prove convergence to an exponential distribution for the length of the smallest sub-interval, with quantitative bounds. The Kakutani process can be embedded in certain branching and fragmentation processes, and we translate our results into that context also. Our proof uses conditioning on an intermediate time, a conditional independence structure for statistics involving small sub-intervals, an Hermite-Edgeworth expansion, and moments estimates with quantitative error bounds.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20749
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Rates of convergence for extremal spacings in Kakutani's random interval-splitting process
Daly, Fraser
Wade, Andrew
Probability
60F05 (Primary) 60G18, 60J80 (Secondary)
Kakutani's random interval-splitting process iteratively divides, via a uniformly random splitting point, the largest sub-interval in a partition of the unit interval. The length of the longest sub-interval after $n$ steps, suitably centred and scaled, is known to satisfy a central limit theorem as $n \to \infty$. We provide a quantitative (Berry-Esseen) upper bound for the finite-$n$ approximation in the central limit theorem, with conjecturally optimal rates in $n$. We also prove convergence to an exponential distribution for the length of the smallest sub-interval, with quantitative bounds. The Kakutani process can be embedded in certain branching and fragmentation processes, and we translate our results into that context also. Our proof uses conditioning on an intermediate time, a conditional independence structure for statistics involving small sub-intervals, an Hermite-Edgeworth expansion, and moments estimates with quantitative error bounds.
title Rates of convergence for extremal spacings in Kakutani's random interval-splitting process
topic Probability
60F05 (Primary) 60G18, 60J80 (Secondary)
url https://arxiv.org/abs/2508.20749