Dynamical origins of the community structure of multi-layer societies

TL;DR

This paper investigates how community structures in multi-layer social networks emerge from social dynamics, using empirical data from an online game and a triadic closure-based voter model to explain observed fragmentation and community size distributions.

Contribution

It introduces a co-evolutionary voter model based on triadic closure that explains community fragmentation and size distributions in multiplex social networks.

Findings

Community size distributions follow power-law or centered around 50 individuals.

The model reproduces the observed fragmentation transition.

Layer similarities align with model predictions.

Abstract

Social structures emerge as a result of individuals managing a variety of different of social relationships. Societies can be represented as highly structured dynamic multiplex networks. Here we study the dynamical origins of the specific community structures of a large-scale social multiplex network of a human society that interacts in a virtual world of a massive multiplayer online game. There we find substantial differences in the community structures of different social actions, represented by the various network layers in the multiplex. Community size distributions are either similar to a power-law or appear to be centered around a size of 50 individuals. To understand these observations we propose a voter model that is built around the principle of triadic closure. It explicitly models the co-evolution of node- and link-dynamics across different layers of the multiplex. Depending on link- and node fluctuation rates, the model exhibits an anomalous shattered fragmentation transition, where one layer fragments from one large component into many small components. The observed community size distributions are in good agreement with the predicted fragmentation in the model. We show that the empirical pairwise similarities of network layers, in terms of link overlap and degree correlations, practically coincide with the model. This suggests that several detailed features of the fragmentation in societies can be traced back to the triadic closure processes.