Masses of blocks of the $Λ$-coalescent with dust via stochastic flows

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1. Verfasser: Véchambre, Grégoire
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Veröffentlicht: 2025
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author Véchambre, Grégoire
author_facet Véchambre, Grégoire
contents We study the masses of blocks of the $Λ$-coalescent with dust and some aspects of their large and small time behaviors. To do so, we start by associating the $Λ$-coalescent to a nested interval-partition constructed from the flow of inverses, introduced by Bertoin and Le Gall in [Ann. inst. Henri Poincare (B) Probab. Stat. 41(3), 307-333 (2003)], of the $Λ$-Fleming-Viot flow, and prove Poisson representations for the masses of blocks in terms of the flow of inverses. The representations enable us to use the power of stochastic calculus to study the masses of blocks. We apply this method to study the long and small time behaviors. In particular, for all $k>1$, we determine the decay rate of the expectation of the $k$-th largest block as time goes to infinity and find that a cut-off phenomenon, related to the presence of dust, occurs: the decay rate is increasing for small indices $k$ but remains constant after a fixed index depending on the measure $Λ$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_01320
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Masses of blocks of the $Λ$-coalescent with dust via stochastic flows
Véchambre, Grégoire
Probability
60J25, 60J76, 60J90, 60G57, 60H05, 92D25
We study the masses of blocks of the $Λ$-coalescent with dust and some aspects of their large and small time behaviors. To do so, we start by associating the $Λ$-coalescent to a nested interval-partition constructed from the flow of inverses, introduced by Bertoin and Le Gall in [Ann. inst. Henri Poincare (B) Probab. Stat. 41(3), 307-333 (2003)], of the $Λ$-Fleming-Viot flow, and prove Poisson representations for the masses of blocks in terms of the flow of inverses. The representations enable us to use the power of stochastic calculus to study the masses of blocks. We apply this method to study the long and small time behaviors. In particular, for all $k>1$, we determine the decay rate of the expectation of the $k$-th largest block as time goes to infinity and find that a cut-off phenomenon, related to the presence of dust, occurs: the decay rate is increasing for small indices $k$ but remains constant after a fixed index depending on the measure $Λ$.
title Masses of blocks of the $Λ$-coalescent with dust via stochastic flows
topic Probability
60J25, 60J76, 60J90, 60G57, 60H05, 92D25
url https://arxiv.org/abs/2503.01320