Convergence Properties of the Asynchronous Maximum Model

Fuente: arXiv
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Auteur principal: Larkin, John
Format: Preprint
Publié: 2024
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author Larkin, John
author_facet Larkin, John
contents Let $G = (V,E)$ be a connected directed graph on $n$ vertices. Assign values from the set $\{1,2,\dots,n\}$ to the vertices of $G$ and update the values according to the following rule: uniformly at random choose a vertex and update its value to the maximum of the values in its neighbourhood. The value at this vertex can potentially decrease. This random process is called the asynchronous maximum model. Repeating this process we show that for a strongly connected directed graph eventually all vertices have the same value and the model is said to have \textit{converged}. In the undirected case the expected convergence time is shown to be asymptotically (as $n\to \infty$) in $Ω(n\log n)$ and $O(n^2)$ and these bounds are tight. We further characterise the convergence time in $O(\frac{n}ϕ\log n)$ where $ϕ$ is the vertex expansion of $G$. This provides a better upper bound for a large class of graphs. Further, we show the number of rounds until convergence is in $O((\frac{n}ϕ\log n)g(n))$ with high probability, where $g(n)$ satisfies $\frac{1}{g^2(n)} \to 0$ as $n \to \infty$. For a strongly connected directed graph the convergence time is shown to be in $O(nb^2 + \frac{n}{ϕ'}\log n)$ where $b$ is a parameter measuring directed cycle length and $ϕ'$ is a parameter measuring vertex expansion.
format Preprint
id arxiv_https___arxiv_org_abs_2406_01910
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Convergence Properties of the Asynchronous Maximum Model
Larkin, John
Data Structures and Algorithms
Probability
Let $G = (V,E)$ be a connected directed graph on $n$ vertices. Assign values from the set $\{1,2,\dots,n\}$ to the vertices of $G$ and update the values according to the following rule: uniformly at random choose a vertex and update its value to the maximum of the values in its neighbourhood. The value at this vertex can potentially decrease. This random process is called the asynchronous maximum model. Repeating this process we show that for a strongly connected directed graph eventually all vertices have the same value and the model is said to have \textit{converged}. In the undirected case the expected convergence time is shown to be asymptotically (as $n\to \infty$) in $Ω(n\log n)$ and $O(n^2)$ and these bounds are tight. We further characterise the convergence time in $O(\frac{n}ϕ\log n)$ where $ϕ$ is the vertex expansion of $G$. This provides a better upper bound for a large class of graphs. Further, we show the number of rounds until convergence is in $O((\frac{n}ϕ\log n)g(n))$ with high probability, where $g(n)$ satisfies $\frac{1}{g^2(n)} \to 0$ as $n \to \infty$. For a strongly connected directed graph the convergence time is shown to be in $O(nb^2 + \frac{n}{ϕ'}\log n)$ where $b$ is a parameter measuring directed cycle length and $ϕ'$ is a parameter measuring vertex expansion.
title Convergence Properties of the Asynchronous Maximum Model
topic Data Structures and Algorithms
Probability
url https://arxiv.org/abs/2406.01910