DSL: Discriminative Subgraph Learning via Sparse Self-Representation

TL;DR

This paper introduces a novel optimization framework called Discriminative Subgraph Learning (DSL) that effectively identifies sparse, connected, and highly discriminative feature subgraphs in network state prediction tasks, improving accuracy and interpretability.

Contribution

The paper presents a unified optimization approach for discriminative subgraph learning that enforces sparsity, connectivity, and discriminative power, advancing beyond prior methods with better control and interpretability.

Findings

Up to 16% accuracy improvement over baselines.

Effective identification of sparse, connected, and discriminative subgraphs.

Reasonable execution time for large instances.

Abstract

The goal in network state prediction (NSP) is to classify the global state (label) associated with features embedded in a graph. This graph structure encoding feature relationships is the key distinctive aspect of NSP compared to classical supervised learning. NSP arises in various applications: gene expression samples embedded in a protein-protein interaction (PPI) network, temporal snapshots of infrastructure or sensor networks, and fMRI coherence network samples from multiple subjects to name a few. Instances from these domains are typically ``wide'' (more features than samples), and thus, feature sub-selection is required for robust and generalizable prediction. How to best employ the network structure in order to learn succinct connected subgraphs encompassing the most discriminative features becomes a central challenge in NSP. Prior work employs connected subgraph sampling or graph smoothing within optimization frameworks, resulting in either large variance of quality or weak control over the connectivity of selected subgraphs. In this work we propose an optimization framework for discriminative subgraph learning (DSL) which simultaneously enforces (i) sparsity, (ii) connectivity and (iii) high discriminative power of the resulting subgraphs of features. Our optimization algorithm is a single-step solution for the NSP and the associated feature selection problem. It is rooted in the rich literature on maximal-margin optimization, spectral graph methods and sparse subspace self-representation. DSL simultaneously ensures solution interpretability and superior predictive power (up to 16% improvement in challenging instances compared to baselines), with execution times up to an hour for large instances.