Support and density of the limit $m$-ary search trees distribution

The space requirements of an $m$-ary search tree satisfies a well-known phase transition: when $m\leq 26$, the second order asymptotics is Gaussian. When $m\geq 27$, it is not Gaussian any longer and a limit $W$ of a complex-valued martingale arises. We show that the distribution of $W$ has a square...

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Main Authors: Brigitte Chauvin, Quansheng Liu, Nicolas Pouyanne
Format: Article
Language:English
Published: Discrete Mathematics & Theoretical Computer Science 2012-01-01
Series:Discrete Mathematics & Theoretical Computer Science
Subjects:
Online Access:https://dmtcs.episciences.org/2994/pdf
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author Brigitte Chauvin
Quansheng Liu
Nicolas Pouyanne
author_facet Brigitte Chauvin
Quansheng Liu
Nicolas Pouyanne
author_sort Brigitte Chauvin
collection DOAJ
description The space requirements of an $m$-ary search tree satisfies a well-known phase transition: when $m\leq 26$, the second order asymptotics is Gaussian. When $m\geq 27$, it is not Gaussian any longer and a limit $W$ of a complex-valued martingale arises. We show that the distribution of $W$ has a square integrable density on the complex plane, that its support is the whole complex plane, and that it has finite exponential moments. The proofs are based on the study of the distributional equation $ W \overset{\mathcal{L}}{=} \sum_{k=1}^mV_k^{\lambda}W_k$, where $V_1, ..., V_m$ are the spacings of $(m-1)$ independent random variables uniformly distributed on $[0,1]$, $W_1, ..., W_m$ are independent copies of W which are also independent of $(V_1, ..., V_m)$ and $\lambda$ is a complex number.
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spelling doaj.art-92ca2e096b5d42a9ade960cef2cae1d12024-03-07T14:50:50ZengDiscrete Mathematics & Theoretical Computer ScienceDiscrete Mathematics & Theoretical Computer Science1365-80502012-01-01DMTCS Proceedings vol. AQ,...Proceedings10.46298/dmtcs.29942994Support and density of the limit $m$-ary search trees distributionBrigitte Chauvin0Quansheng Liu1Nicolas Pouyanne2Laboratoire de Mathématiques de VersaillesLaboratoire de Mathématiques de Bretagne AtlantiqueLaboratoire de Mathématiques de VersaillesThe space requirements of an $m$-ary search tree satisfies a well-known phase transition: when $m\leq 26$, the second order asymptotics is Gaussian. When $m\geq 27$, it is not Gaussian any longer and a limit $W$ of a complex-valued martingale arises. We show that the distribution of $W$ has a square integrable density on the complex plane, that its support is the whole complex plane, and that it has finite exponential moments. The proofs are based on the study of the distributional equation $ W \overset{\mathcal{L}}{=} \sum_{k=1}^mV_k^{\lambda}W_k$, where $V_1, ..., V_m$ are the spacings of $(m-1)$ independent random variables uniformly distributed on $[0,1]$, $W_1, ..., W_m$ are independent copies of W which are also independent of $(V_1, ..., V_m)$ and $\lambda$ is a complex number.https://dmtcs.episciences.org/2994/pdf[math.math-pr] mathematics [math]/probability [math.pr]
spellingShingle Brigitte Chauvin
Quansheng Liu
Nicolas Pouyanne
Support and density of the limit $m$-ary search trees distribution
Discrete Mathematics & Theoretical Computer Science
[math.math-pr] mathematics [math]/probability [math.pr]
title Support and density of the limit $m$-ary search trees distribution
title_full Support and density of the limit $m$-ary search trees distribution
title_fullStr Support and density of the limit $m$-ary search trees distribution
title_full_unstemmed Support and density of the limit $m$-ary search trees distribution
title_short Support and density of the limit $m$-ary search trees distribution
title_sort support and density of the limit m ary search trees distribution
topic [math.math-pr] mathematics [math]/probability [math.pr]
url https://dmtcs.episciences.org/2994/pdf
work_keys_str_mv AT brigittechauvin supportanddensityofthelimitmarysearchtreesdistribution
AT quanshengliu supportanddensityofthelimitmarysearchtreesdistribution
AT nicolaspouyanne supportanddensityofthelimitmarysearchtreesdistribution