Tails of explosive birth processes and applications to non-linear P ólya urns

Fuente: arXiv
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Autori principali: Gottfried, Thomas, Grosskinsky, Stefan
Natura: Preprint
Pubblicazione: 2024
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author Gottfried, Thomas
Grosskinsky, Stefan
author_facet Gottfried, Thomas
Grosskinsky, Stefan
contents We derive a simple expression for the tail-asymptotics of an explosive birth process at a fixed observation time conditioned on non-explosion. Using the well-established exponential embedding, we apply this result to compute the tail distribution of the number of balls of a losing colour in generalized P ólya urn models with super-linear feedback, which are known to exhibit a strong monopoly for the winning colour where losers only win a finite amount. Previous results in this direction were restricted to two colours with the same feedback, which we extend to an arbitrary finite number of colours with individual feedback mechanisms. As an apparent paradox, losing colours with weak feedback are more likely to win in many steps than those with strong feedback. Our approach also allows to characterize the correlations of several losing colours, which provides new insight in the distribution of other related quantities like the total number of balls for losing colours or the time to monopoly. In order to give a complete picture, we also consider sub-linear feedback and discuss asymptotics for a diverging number of colours.
format Preprint
id arxiv_https___arxiv_org_abs_2406_15006
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Tails of explosive birth processes and applications to non-linear P ólya urns
Gottfried, Thomas
Grosskinsky, Stefan
Probability
60J27, 60J05, 91B62, 60J99
We derive a simple expression for the tail-asymptotics of an explosive birth process at a fixed observation time conditioned on non-explosion. Using the well-established exponential embedding, we apply this result to compute the tail distribution of the number of balls of a losing colour in generalized P ólya urn models with super-linear feedback, which are known to exhibit a strong monopoly for the winning colour where losers only win a finite amount. Previous results in this direction were restricted to two colours with the same feedback, which we extend to an arbitrary finite number of colours with individual feedback mechanisms. As an apparent paradox, losing colours with weak feedback are more likely to win in many steps than those with strong feedback. Our approach also allows to characterize the correlations of several losing colours, which provides new insight in the distribution of other related quantities like the total number of balls for losing colours or the time to monopoly. In order to give a complete picture, we also consider sub-linear feedback and discuss asymptotics for a diverging number of colours.
title Tails of explosive birth processes and applications to non-linear P ólya urns
topic Probability
60J27, 60J05, 91B62, 60J99
url https://arxiv.org/abs/2406.15006