The frog model on Galton-Watson trees

Fuente: arXiv
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Main Authors: Michelen, Marcus, Rosenberg, Josh
Format: Preprint
Published: 2019
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author Michelen, Marcus
Rosenberg, Josh
author_facet Michelen, Marcus
Rosenberg, Josh
contents We consider an interacting particle system on trees known as the frog model: initially, a single active particle begins at the root and i.i.d.~$\mathrm{Poiss}(λ)$ many inactive particles are placed at each non-root vertex. Active particles perform discrete time simple random walk and activate the inactive particles they encounter. We show that for Galton-Watson trees with offspring distributions $Z$ satisfying $\mathbf{P}(Z \geq 2) = 1$ and $\mathbf{E}[Z^{4 + ε}] < \infty$ for some $ε> 0$, there is a critical value $λ_c\in(0,\infty)$ separating recurrent and transient regimes for almost surely every tree, thereby answering a question of Hoffman-Johnson-Junge. In addition, we also establish that this critical parameter depends on the entire offspring distribution, not just the maximum value of $Z$, answering another question of Hoffman-Johnson-Junge and showing that the frog model and contact process behave differently on Galton-Watson trees.
format Preprint
id arxiv_https___arxiv_org_abs_1910_02367
institution arXiv
publishDate 2019
record_format arxiv
spellingShingle The frog model on Galton-Watson trees
Michelen, Marcus
Rosenberg, Josh
Probability
60K35
We consider an interacting particle system on trees known as the frog model: initially, a single active particle begins at the root and i.i.d.~$\mathrm{Poiss}(λ)$ many inactive particles are placed at each non-root vertex. Active particles perform discrete time simple random walk and activate the inactive particles they encounter. We show that for Galton-Watson trees with offspring distributions $Z$ satisfying $\mathbf{P}(Z \geq 2) = 1$ and $\mathbf{E}[Z^{4 + ε}] < \infty$ for some $ε> 0$, there is a critical value $λ_c\in(0,\infty)$ separating recurrent and transient regimes for almost surely every tree, thereby answering a question of Hoffman-Johnson-Junge. In addition, we also establish that this critical parameter depends on the entire offspring distribution, not just the maximum value of $Z$, answering another question of Hoffman-Johnson-Junge and showing that the frog model and contact process behave differently on Galton-Watson trees.
title The frog model on Galton-Watson trees
topic Probability
60K35
url https://arxiv.org/abs/1910.02367