Dual Spatial-Temporal Attribution: Architecture-Aligned Post-Hoc Explainability for Recurrent Graph Anomaly Detection
This work addresses the limited interpretability of dynamic graph anomaly detection models, which hinders their applicability in audit and trustworthy decision-making scenarios. The authors propose X-AddGraph, the first post-hoc explainability method tailored for the AddGraph framework. By introducing an architecture-aligned, three-component attribution mechanism, X-AddGraph jointly explains spatial structure, short-term temporal attention, and long-term recurrent states without compromising the original model’s performance. The approach integrates gradient-based attribution, attention weight inspection, and hidden state backtracking to deliver precise, reproducible explanations. Evaluated on the UCI Message dataset, the method achieves a reproduced AUC of 0.8705, with long-term temporal attribution significantly outperforming random baselines (0.127 vs. 0.074), thereby offering both high fidelity and comprehensive interpretability.