Inverting the operation of conditioning a branching process on extinction

Fuente: arXiv
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Auteurs principaux: Gwynne, Ewain, Liu, Jiaqi
Format: Preprint
Publié: 2024
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author Gwynne, Ewain
Liu, Jiaqi
author_facet Gwynne, Ewain
Liu, Jiaqi
contents It is well-known that conditioning a supercritical (multi-type) branching process on the event that it eventually becomes extinct yields a subcritical branching process. We study the corresponding inverse problem: given a subcritical branching process, does there exist a supercritical branching process with the property that when we condition it on extinction, we get back the original subcritical branching process? We show that such a supercritical branching process (which we call a conjugate branching process) exists under mild hypotheses on the original subcritical branching process. We also show by example that if there are at least two types, then the conjugate branching process is not necessarily unique. Our results are relevant to the problem of constructing natural random planar maps whose scaling limit is given by supercritical Liouville quantum gravity. Moreover, conjugate branching processes can also be used to give alternative evolutionary hypotheses in cancer modeling.
format Preprint
id arxiv_https___arxiv_org_abs_2411_06301
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Inverting the operation of conditioning a branching process on extinction
Gwynne, Ewain
Liu, Jiaqi
Probability
Primary 60J80, Secondary 47H10, 60J85
It is well-known that conditioning a supercritical (multi-type) branching process on the event that it eventually becomes extinct yields a subcritical branching process. We study the corresponding inverse problem: given a subcritical branching process, does there exist a supercritical branching process with the property that when we condition it on extinction, we get back the original subcritical branching process? We show that such a supercritical branching process (which we call a conjugate branching process) exists under mild hypotheses on the original subcritical branching process. We also show by example that if there are at least two types, then the conjugate branching process is not necessarily unique. Our results are relevant to the problem of constructing natural random planar maps whose scaling limit is given by supercritical Liouville quantum gravity. Moreover, conjugate branching processes can also be used to give alternative evolutionary hypotheses in cancer modeling.
title Inverting the operation of conditioning a branching process on extinction
topic Probability
Primary 60J80, Secondary 47H10, 60J85
url https://arxiv.org/abs/2411.06301