Contact process for the spread of knowledge

Fuente: arXiv
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Autores principales: Lanchier, Nicolas, Mercer, Max, Yun, Hyunsik
Formato: Preprint
Publicado: 2025
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author Lanchier, Nicolas
Mercer, Max
Yun, Hyunsik
author_facet Lanchier, Nicolas
Mercer, Max
Yun, Hyunsik
contents This paper is concerned with a natural variant of the contact process modeling the spread of knowledge on the integer lattice. Each site is characterized by its knowledge, measured by a real number ranging from 0 = ignorant to 1 = omniscient. Neighbors interact at rate $λ$, which results in both neighbors attempting to teach each other a fraction $μ$ of their knowledge, and individuals die at rate one, which results in a new individual with no knowledge. Starting with a single omniscient site, our objective is to study whether the total amount of knowledge on the lattice converges to zero (extinction) or remains bounded away from zero (survival). The process dies out when $λ\leq λ_c$ and/or $μ= 0$, where $λ_c$ denotes the critical value of the contact process. In contrast, we prove that, for all $λ> λ_c$, there is a unique phase transition in the direction of $μ$, and for all $μ> 0$, there is a unique phase transition in the direction of $λ$. Our proof of survival relies on block constructions showing more generally convergence of the knowledge to infinity, while our proof of extinction relies on martingale techniques showing more generally an exponential decay of the knowledge.
format Preprint
id arxiv_https___arxiv_org_abs_2503_17260
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Contact process for the spread of knowledge
Lanchier, Nicolas
Mercer, Max
Yun, Hyunsik
Probability
60K35, 91D25
This paper is concerned with a natural variant of the contact process modeling the spread of knowledge on the integer lattice. Each site is characterized by its knowledge, measured by a real number ranging from 0 = ignorant to 1 = omniscient. Neighbors interact at rate $λ$, which results in both neighbors attempting to teach each other a fraction $μ$ of their knowledge, and individuals die at rate one, which results in a new individual with no knowledge. Starting with a single omniscient site, our objective is to study whether the total amount of knowledge on the lattice converges to zero (extinction) or remains bounded away from zero (survival). The process dies out when $λ\leq λ_c$ and/or $μ= 0$, where $λ_c$ denotes the critical value of the contact process. In contrast, we prove that, for all $λ> λ_c$, there is a unique phase transition in the direction of $μ$, and for all $μ> 0$, there is a unique phase transition in the direction of $λ$. Our proof of survival relies on block constructions showing more generally convergence of the knowledge to infinity, while our proof of extinction relies on martingale techniques showing more generally an exponential decay of the knowledge.
title Contact process for the spread of knowledge
topic Probability
60K35, 91D25
url https://arxiv.org/abs/2503.17260