Leaf multiplicity in a Bienaym\'e-Galton-Watson tree

This note defines a notion of multiplicity for nodes in a rooted tree and presents an asymptotic calculation of the maximum multiplicity over all leaves in a Bienaym\'e-Galton-Watson tree with critical offspring distribution $\xi$, conditioned on the tree being of size $n$. In particular, we sh...

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Main Authors: Anna M. Brandenberger, Luc Devroye, Marcel K. Goh, Rosie Y. Zhao
Format: Article
Language:English
Published: Discrete Mathematics & Theoretical Computer Science 2022-03-01
Series:Discrete Mathematics & Theoretical Computer Science
Subjects:
Online Access:https://dmtcs.episciences.org/7515/pdf
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author Anna M. Brandenberger
Luc Devroye
Marcel K. Goh
Rosie Y. Zhao
author_facet Anna M. Brandenberger
Luc Devroye
Marcel K. Goh
Rosie Y. Zhao
author_sort Anna M. Brandenberger
collection DOAJ
description This note defines a notion of multiplicity for nodes in a rooted tree and presents an asymptotic calculation of the maximum multiplicity over all leaves in a Bienaym\'e-Galton-Watson tree with critical offspring distribution $\xi$, conditioned on the tree being of size $n$. In particular, we show that if $S_n$ is the maximum multiplicity in a conditional Bienaym\'e-Galton-Watson tree, then $S_n = \Omega(\log n)$ asymptotically in probability and under the further assumption that ${\bf E}\{2^\xi\} < \infty$, we have $S_n = O(\log n)$ asymptotically in probability as well. Explicit formulas are given for the constants in both bounds. We conclude by discussing links with an alternate definition of multiplicity that arises in the root-estimation problem.
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spelling doaj.art-e1cfe43e361746acb0ac3c29040d1d912024-03-07T15:46:22ZengDiscrete Mathematics & Theoretical Computer ScienceDiscrete Mathematics & Theoretical Computer Science1365-80502022-03-01vol. 24, no. 1Analysis of Algorithms10.46298/dmtcs.75157515Leaf multiplicity in a Bienaym\'e-Galton-Watson treeAnna M. BrandenbergerLuc DevroyeMarcel K. GohRosie Y. ZhaoThis note defines a notion of multiplicity for nodes in a rooted tree and presents an asymptotic calculation of the maximum multiplicity over all leaves in a Bienaym\'e-Galton-Watson tree with critical offspring distribution $\xi$, conditioned on the tree being of size $n$. In particular, we show that if $S_n$ is the maximum multiplicity in a conditional Bienaym\'e-Galton-Watson tree, then $S_n = \Omega(\log n)$ asymptotically in probability and under the further assumption that ${\bf E}\{2^\xi\} < \infty$, we have $S_n = O(\log n)$ asymptotically in probability as well. Explicit formulas are given for the constants in both bounds. We conclude by discussing links with an alternate definition of multiplicity that arises in the root-estimation problem.https://dmtcs.episciences.org/7515/pdfmathematics - probability
spellingShingle Anna M. Brandenberger
Luc Devroye
Marcel K. Goh
Rosie Y. Zhao
Leaf multiplicity in a Bienaym\'e-Galton-Watson tree
Discrete Mathematics & Theoretical Computer Science
mathematics - probability
title Leaf multiplicity in a Bienaym\'e-Galton-Watson tree
title_full Leaf multiplicity in a Bienaym\'e-Galton-Watson tree
title_fullStr Leaf multiplicity in a Bienaym\'e-Galton-Watson tree
title_full_unstemmed Leaf multiplicity in a Bienaym\'e-Galton-Watson tree
title_short Leaf multiplicity in a Bienaym\'e-Galton-Watson tree
title_sort leaf multiplicity in a bienaym e galton watson tree
topic mathematics - probability
url https://dmtcs.episciences.org/7515/pdf
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AT lucdevroye leafmultiplicityinabienaymegaltonwatsontree
AT marcelkgoh leafmultiplicityinabienaymegaltonwatsontree
AT rosieyzhao leafmultiplicityinabienaymegaltonwatsontree