The World Wide Web Conference | 2019
Nonlinear Diffusion for Community Detection and Semi-Supervised Learning
Abstract
Diffusions, such as the heat kernel diffusion and the PageRank vector, and their relatives are widely used graph mining primitives that have been successful in a variety of contexts including community detection and semi-supervised learning. The majority of existing methods and methodology involves linear diffusions, which then yield simple algorithms involving repeated matrix-vector operations. Recent work, however, has shown that sophisticated and complicated techniques based on network embeddings and neural networks can give empirical results superior to those based on linear diffusions. In this paper, we illustrate a class of nonlinear graph diffusions that are competitive with state of the art embedding techniques and outperform classic diffusions. Our new methods enjoy much of the simplicity underlying classic diffusion methods as well. Formally, they are based on nonlinear dynamical systems that can be realized with an implementation akin to applying a nonlinear function after each matrix-vector product in a classic diffusion. This framework also enables us to easily integrate results from multiple data representations in a principled fashion. Furthermore, we have some theoretical relationships that suggest choices of the nonlinear term. We demonstrate the benefits of these techniques on a variety of synthetic and real-world data.