Self-Organizing Flows in Social Networks

TL;DR

This paper investigates how self-organization in social networks affects the efficiency of social filtering, revealing conditions under which stable and efficient information dissemination emerges or fails due to user interest heterogeneity.

Contribution

It introduces flow games to model network formation with selfish users and analyzes convergence and efficiency under different interest structures.

Findings

Selfish dynamics converge to near-optimal structures with homogeneous interests.

Heterogeneous interests can lead to arbitrarily inefficient information dissemination.

Low doubling dimension interest spaces ensure convergence and complete information access.

Abstract

Social networks offer users new means of accessing information, essentially relying on "social filtering", i.e. propagation and filtering of information by social contacts. The sheer amount of data flowing in these networks, combined with the limited budget of attention of each user, makes it difficult to ensure that social filtering brings relevant content to the interested users. Our motivation in this paper is to measure to what extent self-organization of the social network results in efficient social filtering. To this end we introduce flow games, a simple abstraction that models network formation under selfish user dynamics, featuring user-specific interests and budget of attention. In the context of homogeneous user interests, we show that selfish dynamics converge to a stable network structure (namely a pure Nash equilibrium) with close-to-optimal information dissemination. We show in contrast, for the more realistic case of heterogeneous interests, that convergence, if it occurs, may lead to information dissemination that can be arbitrarily inefficient, as captured by an unbounded "price of anarchy". Nevertheless the situation differs when users' interests exhibit a particular structure, captured by a metric space with low doubling dimension. In that case, natural autonomous dynamics converge to a stable configuration. Moreover, users obtain all the information of interest to them in the corresponding dissemination, provided their budget of attention is logarithmic in the size of their interest set.