FreeGAD: A Training-Free yet Effective Approach for Graph Anomaly Detection

Fuente: arXiv
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Main Authors: Zhao, Yunfeng, Liu, Yixin, Li, Shiyuan, Chen, Qingfeng, Zheng, Yu, Pan, Shirui
Format: Preprint
Published: 2025
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author Zhao, Yunfeng
Liu, Yixin
Li, Shiyuan
Chen, Qingfeng
Zheng, Yu
Pan, Shirui
author_facet Zhao, Yunfeng
Liu, Yixin
Li, Shiyuan
Chen, Qingfeng
Zheng, Yu
Pan, Shirui
contents Graph Anomaly Detection (GAD) aims to identify nodes that deviate from the majority within a graph, playing a crucial role in applications such as social networks and e-commerce. Despite the current advancements in deep learning-based GAD, existing approaches often suffer from high deployment costs and poor scalability due to their complex and resource-intensive training processes. Surprisingly, our empirical findings suggest that the training phase of deep GAD methods, commonly perceived as crucial, may actually contribute less to anomaly detection performance than expected. Inspired by this, we propose FreeGAD, a novel training-free yet effective GAD method. Specifically, it leverages an affinity-gated residual encoder to generate anomaly-aware representations. Meanwhile, FreeGAD identifies anchor nodes as pseudo-normal and anomalous guides, followed by calculating anomaly scores through anchor-guided statistical deviations. Extensive experiments demonstrate that FreeGAD achieves superior anomaly detection performance, efficiency, and scalability on multiple benchmark datasets from diverse domains, without any training or iterative optimization.
format Preprint
id arxiv_https___arxiv_org_abs_2508_10594
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle FreeGAD: A Training-Free yet Effective Approach for Graph Anomaly Detection
Zhao, Yunfeng
Liu, Yixin
Li, Shiyuan
Chen, Qingfeng
Zheng, Yu
Pan, Shirui
Machine Learning
Artificial Intelligence
Graph Anomaly Detection (GAD) aims to identify nodes that deviate from the majority within a graph, playing a crucial role in applications such as social networks and e-commerce. Despite the current advancements in deep learning-based GAD, existing approaches often suffer from high deployment costs and poor scalability due to their complex and resource-intensive training processes. Surprisingly, our empirical findings suggest that the training phase of deep GAD methods, commonly perceived as crucial, may actually contribute less to anomaly detection performance than expected. Inspired by this, we propose FreeGAD, a novel training-free yet effective GAD method. Specifically, it leverages an affinity-gated residual encoder to generate anomaly-aware representations. Meanwhile, FreeGAD identifies anchor nodes as pseudo-normal and anomalous guides, followed by calculating anomaly scores through anchor-guided statistical deviations. Extensive experiments demonstrate that FreeGAD achieves superior anomaly detection performance, efficiency, and scalability on multiple benchmark datasets from diverse domains, without any training or iterative optimization.
title FreeGAD: A Training-Free yet Effective Approach for Graph Anomaly Detection
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2508.10594