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Cover time for branching random walks on regular trees

Published online by Cambridge University Press:  09 February 2022

Matthew I. Roberts*
Affiliation:
University of Bath
*
*Postal address: Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, UK. Email address: mattiroberts@gmail.com

Abstract

Let T be the regular tree in which every vertex has exactly $d\ge 3$ neighbours. Run a branching random walk on T, in which at each time step every particle gives birth to a random number of children with mean d and finite variance, and each of these children moves independently to a uniformly chosen neighbour of its parent. We show that, starting with one particle at some vertex 0 and conditionally on survival of the process, the time it takes for every vertex within distance r of 0 to be hit by a particle of the branching random walk is $r + ({2}/{\log(3/2)})\log\log r + {\mathrm{o}}(\log\log r)$ .

Type
Original Article
Copyright
© The Author(s), 2022. Published by Cambridge University Press on behalf of Applied Probability Trust

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