First passage percolation on the Newman-Watts small world model

TL;DR

This paper studies the typical distances and epidemic spread in a Newman-Watts small world graph with exponential edge weights, revealing logarithmic growth, distributional limits, and a CLT for shortest paths.

Contribution

It introduces a detailed analysis of passage times and shortest paths in the weighted Newman-Watts model, including distributional results and epidemic modeling insights.

Findings

Typical distances grow as (1/λ) log n

Number of edges in shortest path follows a CLT

Infection fraction follows a deterministic curve with random shift

Abstract

The Newman-Watts model is given by taking a cycle graph of n vertices and then adding each possible edge $(i,j), |i-j|\neq 1 \mod n$ with probability $\rho/n$ for some $\rho>0$ constant. In this paper we add i.i.d. exponential edge weights to this graph, and investigate typical distances in the corresponding random metric space given by the least weight paths between vertices. We show that typical distances grow as $\frac1\lambda \log n$ for a $\lambda>0$ and determine the distribution of smaller order terms in terms of limits of branching process random variables. We prove that the number of edges along the shortest weight path follows a Central Limit Theorem, and show that in a corresponding epidemic spread model the fraction of infected vertices follows a deterministic curve with a random shift.