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Anomaly detection from graph data has drawn much attention due to its practical significance in many critical applications including cybersecurity, finance, and social networks. Existing data mining and machine learning methods are either…

Machine Learning · Computer Science 2022-01-25 Yu Zheng , Ming Jin , Yixin Liu , Lianhua Chi , Khoa T. Phan , Yi-Ping Phoebe Chen

Graph Neural Networks (GNNs) have achieved promising results in tasks such as node classification and graph classification. However, recent studies reveal that GNNs are vulnerable to backdoor attacks, posing a significant threat to their…

Machine Learning · Computer Science 2025-03-13 Zhiwei Zhang , Minhua Lin , Junjie Xu , Zongyu Wu , Enyan Dai , Suhang Wang

Graph anomaly detection (GAD) is widely applied in many areas, such as financial fraud detection and social spammer detection. Anomalous nodes in the graph not only impact their own communities but also create a ripple effect on neighbors…

Machine Learning · Computer Science 2026-01-19 Zhu Wang , Junnan Dong , Shuang Zhou , Chang Yang , Shengjie Zhao , Xiao Huang

Trajectory anomaly detection is essential for identifying unusual and unexpected movement patterns in applications ranging from intelligent transportation systems to urban safety and fraud prevention. Existing methods only consider limited…

Machine Learning · Computer Science 2025-09-24 Jonathan Kabala Mbuya , Dieter Pfoser , Antonios Anastasopoulos

Graph anomaly detection (GAD) is a vital task since even a few anomalies can pose huge threats to benign users. Recent semi-supervised GAD methods, which can effectively leverage the available labels as prior knowledge, have achieved…

Machine Learning · Computer Science 2023-06-21 Shuang Zhou , Xiao Huang , Ninghao Liu , Huachi Zhou , Fu-Lai Chung , Long-Kai Huang

Graph anomaly detection (GAD) is a vital task since even a few anomalies can pose huge threats to benign users. Recent semi-supervised GAD methods, which can effectively leverage the available labels as prior knowledge, have achieved…

Machine Learning · Computer Science 2023-07-25 Shuang Zhou , Xiao Huang , Ninghao Liu , Fu-Lai Chung , Long-Kai Huang

Graph anomaly detection has attracted considerable attention from various domain ranging from network security to finance in recent years. Due to the fact that labeling is very costly, existing methods are predominately developed in an…

Machine Learning · Computer Science 2024-04-15 Hwan Kim , Junghoon Kim , Byung Suk Lee , Sungsu Lim

A novel unsupervised outlier score, which can be embedded into graph based dimensionality reduction techniques, is presented in this work. The score uses the directed nearest neighbor graphs of those techniques. Hence, the same measure of…

Machine Learning · Computer Science 2021-05-06 Jonas Wurst , Alberto Flores Fernández , Michael Botsch , Wolfgang Utschick

A significant number of anomalous nodes in the real world, such as fake news, noncompliant users, malicious transactions, and malicious posts, severely compromises the health of the graph data ecosystem and urgently requires effective…

Machine Learning · Computer Science 2026-03-11 Xiong Zhang , Hong Peng , Changlong Fu , Xin Jin , Yun Yang , Cheng Xie

Existing methods for graph out-of-distribution (OOD) detection typically depend on training graph neural network (GNN) classifiers using a substantial amount of labeled in-distribution (ID) data. However, acquiring high-quality labeled…

Machine Learning · Computer Science 2025-03-31 Haoyan Xu , Zhengtao Yao , Yushun Dong , Ziyi Wang , Ryan A. Rossi , Mengyuan Li , Yue Zhao

In the context of modern machine learning, models deployed in real-world scenarios often encounter diverse data shifts like covariate and semantic shifts, leading to challenges in both out-of-distribution (OOD) generalization and detection.…

Machine Learning · Computer Science 2024-09-30 Han Wang , Yixuan Li

A key feature of out-of-distribution (OOD) detection is to exploit a trained neural network by extracting statistical patterns and relationships through the multi-layer classifier to detect shifts in the expected input data distribution.…

Machine Learning · Computer Science 2023-06-07 Eduardo Dadalto , Pierre Colombo , Guillaume Staerman , Nathan Noiry , Pablo Piantanida

Deep neural networks (DNNs) are known to produce incorrect predictions with very high confidence on out-of-distribution (OOD) inputs. This limitation is one of the key challenges in the adoption of deep learning models in high-assurance…

Machine Learning · Computer Science 2021-03-24 Ramneet Kaur , Susmit Jha , Anirban Roy , Oleg Sokolsky , Insup Lee

The task of graph-level anomaly detection (GLAD) is to identify anomalous graphs that deviate significantly from the majority of graphs in a dataset. While deep GLAD methods have shown promising performance, their black-box nature limits…

Machine Learning · Computer Science 2026-02-12 Qiuran Zhao , Kai Ming Ting , Xinpeng Li

Graph Anomaly Detection (GAD) aims to identify atypical graph entities, such as nodes, edges, or substructures, that deviate significantly from the majority. While existing text-rich approaches typically integrate structural context into…

Computation and Language · Computer Science 2026-05-20 Wen Shi , Zhe Wang , Huafei Huang , Qing Qing , Ziqi Xu , Qixin Zhang , Xikun Zhang , Renqiang Luo , Feng Xia

Graph Neural Networks (GNNs) have achieved impressive performance in graph-related tasks. However, they suffer from poor generalization on out-of-distribution (OOD) data, as they tend to learn spurious correlations. Such correlations…

Machine Learning · Statistics 2026-03-26 Bowen Lu , Liangqiang Yang , Teng Li

Outlier detection has gained increasing interest in recent years, due to newly emerging technologies and the huge amount of high-dimensional data that are now available. Outlier detection can help practitioners to identify unwanted noise…

Statistics Theory · Mathematics 2021-05-20 Mads Lindskou , Torben Tvedebrink , Poul Svante Eriksen , Niels Morling

Graph anomaly detection is crucial for identifying nodes that deviate from regular behavior within graphs, benefiting various domains such as fraud detection and social network. Although existing reconstruction-based methods have achieved…

Machine Learning · Computer Science 2023-12-25 Junwei He , Qianqian Xu , Yangbangyan Jiang , Zitai Wang , Qingming Huang

Many computer vision tasks involve processing large amounts of data contaminated by outliers, which need to be detected and rejected. While outlier detection methods based on robust statistics have existed for decades, only recently have…

Computer Vision and Pattern Recognition · Computer Science 2017-04-14 Chong You , Daniel P. Robinson , René Vidal

Water is the lifeblood of river networks, and its quality plays a crucial role in sustaining both aquatic ecosystems and human societies. Real-time monitoring of water quality is increasingly reliant on in-situ sensor technology. Anomaly…

Machine Learning · Computer Science 2023-06-02 Katie Buchhorn , Edgar Santos-Fernandez , Kerrie Mengersen , Robert Salomone
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