Concentration in Gossip Opinion Dynamics over Random Graphs

TL;DR

This paper establishes concentration inequalities for gossip opinion dynamics on random graphs, providing bounds on how the final opinions over random networks relate to those over an expected graph, with implications for opinion polarization.

Contribution

The paper introduces a novel concentration inequality framework for gossip opinion dynamics on random graphs, linking network structure to opinion outcomes.

Findings

High-probability bounds for opinion differences between random and expected graphs

Demonstration of opinion polarization when stubborn influence is large

Validation of theoretical results through simulations on stochastic block models

Abstract

We study concentration inequalities in gossip opinion dynamics over random graphs. In the model, a network is generated from a random graph model with independent edges, and agents interact pairwise randomly over the network. During the process, regular agents average neighbors' opinions and then update, whereas stubborn agents do not change opinions. To approximate the original process, we introduce a gossip model over an expected graph, obtained by averaging all possible networks generated from the random graph model. Using concentration inequalities, we derive high-probability bounds for the distance between the expected final opinion vectors over the random graph and over the expected graph. Leveraging matrix perturbation results, we show how such concentration can help study the effect of network structure on the expected final opinions in two cases: (i) When the influence of stubborn agents is large, the expected final opinions polarize and are close to stubborn agents' opinions. (ii) When the influence of stubborn agents is small, the expected final opinions are close to each other. With the help of concentration inequalities for Markov chains, we obtain high-probability bounds for the distance between time-averaged opinions and the expected final opinions over the expected graph. In simulation, we validate the theoretical findings, and study a gossip model over a stochastic block model that has community structure.