The number of particles in activated random walk on the complete graph

Fuente: arXiv
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Autori principali: Járai, Antal A., Mönch, Christian, Taggi, Lorenzo
Natura: Preprint
Pubblicazione: 2023
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author Járai, Antal A.
Mönch, Christian
Taggi, Lorenzo
author_facet Járai, Antal A.
Mönch, Christian
Taggi, Lorenzo
contents We consider an elementary model for self-organised criticality, the activated random walk on the complete graph. We introduce a discrete time Markov chain as follows. At each time step, we add an active particle at a random vertex and let the system stabilise following the activated random walk dynamics, obtaining a particle configuration with all sleeping particles. Particles visiting a boundary vertex are removed from the system. We characterise the support of the stationary distribution of this Markov chain, showing that, with high probability, the number of particles concentrates around the value $ρ_c N + a \sqrt{N \log N}$ with fluctuations of order at most $o( \sqrt{N \log N })$, where $N$ is the number of vertices. Due to the mean-field nature of the model, we are able to determine precisely the critical density $ρ_c= \fracλ{1+λ}$, where $λ$ is the sleeping rate, as well as the constant $a = \sqrtλ / (1 + λ) $ characterising the lower order shift. Our approach utilises results about super-martingales associated with activated random walk that are of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2304_10169
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The number of particles in activated random walk on the complete graph
Járai, Antal A.
Mönch, Christian
Taggi, Lorenzo
Probability
Primary 82C22, Secondary 60K35, 82C26
We consider an elementary model for self-organised criticality, the activated random walk on the complete graph. We introduce a discrete time Markov chain as follows. At each time step, we add an active particle at a random vertex and let the system stabilise following the activated random walk dynamics, obtaining a particle configuration with all sleeping particles. Particles visiting a boundary vertex are removed from the system. We characterise the support of the stationary distribution of this Markov chain, showing that, with high probability, the number of particles concentrates around the value $ρ_c N + a \sqrt{N \log N}$ with fluctuations of order at most $o( \sqrt{N \log N })$, where $N$ is the number of vertices. Due to the mean-field nature of the model, we are able to determine precisely the critical density $ρ_c= \fracλ{1+λ}$, where $λ$ is the sleeping rate, as well as the constant $a = \sqrtλ / (1 + λ) $ characterising the lower order shift. Our approach utilises results about super-martingales associated with activated random walk that are of independent interest.
title The number of particles in activated random walk on the complete graph
topic Probability
Primary 82C22, Secondary 60K35, 82C26
url https://arxiv.org/abs/2304.10169