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Growth of Integral Transforms and Extinction in Critical Galton-Watson Processes

Published online by Cambridge University Press:  14 July 2016

Daniel Tokarev*
Affiliation:
The University of Melbourne
*
Postal address: Australian Research Council Centre of Excellence for Mathematics and Statistics of Complex Systems (MASCOS), The University of Melbourne, 139 Barry Street, Carlton, VIC 3010, Australia. Email address: [email protected]
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Abstract

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The mean time to extinction of a critical Galton-Watson process with initial population size k is shown to be asymptotically equivalent to two integral transforms: one involving the kth iterate of the probability generating function and one involving the generating function itself. Relating the growth of these transforms to the regular variation of their arguments, immediately connects statements involving the regular variation of the probability generating function, its iterates at 0, the quasistationary measures, their partial sums, and the limiting distribution of the time to extinction. In the critical case of finite variance we also give the growth of the mean time to extinction, conditioned on extinction occurring by time n.

Type
Research Article
Copyright
Copyright © Applied Probability Trust 2008 

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