Balanced and fragmented phases in societies with homophily and social balance

TL;DR

This paper demonstrates that social systems with homophily and social balance can reach balanced, fragmented states for any number of attributes if individuals consider a significant fraction of their triadic relations, extending previous restrictive results.

Contribution

It introduces a Hamiltonian model showing that balanced, fragmented social states are achievable regardless of attribute count when individuals account for multiple triadic relations.

Findings

Balanced states occur above a critical fraction q_c of triadic relations considered.

Results hold for both dense and sparse social networks.

In the limit of small q, findings align with previous restrictive models.

Abstract

Recent attempts to understand the origin of social fragmentation are based on spin models which include terms accounting for two social phenomena: homophily -- the tendency for people with similar opinions to establish positive relations -- and social balance -- the tendency for people to establish balanced triadic relations. Spins represent attribute vectors that encode multiple (binary) opinions of individuals and social interactions between individuals can be positive or negative. Recent work suggests that large systems of N >> 1 individuals never reach a balanced state (where unbalanced triads with one or three hostile links remain), provided the number of attributes for each agent is less than O(N^2) [Phys. Rev. Lett. 125, 078302]. Here we show that this statement is overly restrictive. Within a Hamiltonian framework that minimizes individuals' social stress, we demonstrate that stationary, balanced, but fragmented states can be reached for any number of attributes, if, in addition to homophily, individuals take into account a significant fraction, q, of their triadic relations. Above a critical value q_c, balanced states result. This result also holds for sparse realistic social networks. Finally, in the limit of small q, our result agrees with that of [Phys. Rev. Lett. 125, 078302].