Community detection in multi-relational data with restricted multi-layer stochastic blockmodel

TL;DR

This paper introduces and analyzes the restricted multi-layer stochastic blockmodel (RMLSBM) for community detection in multi-relational data, demonstrating its advantages over existing models through theoretical results and empirical validation.

Contribution

The paper develops the RMLSBM, derives consistency and minimax error rates, and compares its performance with other methods, showing its superiority in certain growth scenarios.

Findings

RMLSBM outperforms MLSBM when community growth is high or degrees are low.

Consistency results are established for maximum likelihood estimators in multi-layer models.

Simulation and real data confirm the effectiveness of multi-layer approaches.

Abstract

In recent years there has been an increased interest in statistical analysis of data with multiple types of relations among a set of entities. Such multi-relational data can be represented as multi-layer graphs where the set of vertices represents the entities and multiple types of edges represent the different relations among them. For community detection in multi-layer graphs, we consider two random graph models, the multi-layer stochastic blockmodel (MLSBM) and a model with a restricted parameter space, the restricted multi-layer stochastic blockmodel (RMLSBM). We derive consistency results for community assignments of the maximum likelihood estimators (MLEs) in both models where MLSBM is assumed to be the true model, and either the number of nodes or the number of types of edges or both grow. We compare MLEs in the two models with other baseline approaches, such as separate modeling of layers, aggregating the layers and majority voting. RMLSBM is shown to have advantage over MLSBM when either the growth rate of the number of communities is high or the growth rate of the average degree of the component graphs in the multi-graph is low. We also derive minimax rates of error and sharp thresholds for achieving consistency of community detection in both models, which are then used to compare the multi-layer models with a baseline model, the aggregate stochastic block model. The simulation studies and real data applications confirm the superior performance of the multi-layer approaches in comparison to the baseline procedures.