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There is growing interest in applying graph-based methods to Time Series Anomaly Detection (TSAD), particularly Graph Neural Networks (GNNs), as they naturally model dependencies among multivariate signals. GNNs are typically used as…

Machine Learning · Computer Science 2026-03-11 Federico Bello , Gonzalo Chiarlone , Marcelo Fiori , Gastón García González , Federico Larroca

Graph anomaly detection (GAD) has garnered increasing attention in recent years, yet remains challenging due to two key factors: (1) label scarcity stemming from the high cost of annotations and (2) homophily disparity at node and class…

Machine Learning · Computer Science 2026-01-30 Yunhui Liu , Jiashun Cheng , Yiqing Lin , Qizhuo Xie , Jia Li , Fugee Tsung , Hongzhi Yin , Tao Zheng , Jianhua Zhao , Tieke He

Graph-based fraud detection has heretofore received considerable attention. Owning to the great success of Graph Neural Networks (GNNs), many approaches adopting GNNs for fraud detection has been gaining momentum. However, most existing…

Machine Learning · Computer Science 2022-10-25 Zhixun Li , Dingshuo Chen , Qiang Liu , Shu Wu

Combining Graph neural networks (GNNs) with contrastive learning for anomaly detection has drawn rising attention recently. Existing graph contrastive anomaly detection (GCAD) methods have primarily focused on improving detection capability…

Machine Learning · Computer Science 2023-05-05 Zhiyuan Liu , Chunjie Cao , Fangjian Tao , Jingzhang Sun

Many recent works have studied the performance of Graph Neural Networks (GNNs) in the context of graph homophily - a label-dependent measure of connectivity. Traditional GNNs generate node embeddings by aggregating information from a node's…

Machine Learning · Computer Science 2021-06-08 Hesham Mostafa , Marcel Nassar , Somdeb Majumdar

Anomaly detection is a crucial task in complex distributed systems. A thorough understanding of the requirements and challenges of anomaly detection is pivotal to the security of such systems, especially for real-world deployment. While…

Graph Neural Networks (GNNs) have risen to prominence in learning representations for graph structured data. A single GNN layer typically consists of a feature transformation and a feature aggregation operation. The former normally uses…

Machine Learning · Computer Science 2021-10-19 Yao Ma , Xiaorui Liu , Tong Zhao , Yozen Liu , Jiliang Tang , Neil Shah

Most existing deep learning models are trained based on the closed-world assumption, where the test data is assumed to be drawn i.i.d. from the same distribution as the training data, known as in-distribution (ID). However, when models are…

Machine Learning · Computer Science 2022-11-09 Yixin Liu , Kaize Ding , Huan Liu , Shirui Pan

Imbalanced node classification widely exists in real-world networks where graph neural networks (GNNs) are usually highly inclined to majority classes and suffer from severe performance degradation on classifying minority class nodes.…

Artificial Intelligence · Computer Science 2023-05-01 Jie Liu , Mengting He , Guangtao Wang , Nguyen Quoc Viet Hung , Xuequn Shang , Hongzhi Yin

Recent research on the robustness of Graph Neural Networks (GNNs) under noises or attacks has attracted great attention due to its importance in real-world applications. Most previous methods explore a single noise source, recovering…

Machine Learning · Computer Science 2024-08-02 Tianmeng Yang , Jiahao Meng , Min Zhou , Yaming Yang , Yujing Wang , Xiangtai Li , Yunhai Tong

Graph-level anomaly detection (GLAD) aims to identify graphs that exhibit notable dissimilarity compared to the majority in a collection. However, current works primarily focus on evaluating graph-level abnormality while failing to provide…

Machine Learning · Computer Science 2023-10-26 Yixin Liu , Kaize Ding , Qinghua Lu , Fuyi Li , Leo Yu Zhang , Shirui Pan

Homophily is a graph property describing the tendency of edges to connect similar nodes; the opposite is called heterophily. It is often believed that heterophilous graphs are challenging for standard message-passing graph neural networks…

Social and Information Networks · Computer Science 2024-04-17 Oleg Platonov , Denis Kuznedelev , Artem Babenko , Liudmila Prokhorenkova

Graph unlearning, which deletes graph elements such as nodes and edges from trained graph neural networks (GNNs), is crucial for real-world applications where graph data may contain outdated, inaccurate, or privacy-sensitive information.…

Machine Learning · Computer Science 2025-05-20 Pengfei Ding , Yan Wang , Guanfeng Liu , Jiajie Zhu

Graph neural networks (GNNs) have achieved remarkable advances in graph-oriented tasks. However, real-world graphs invariably contain a certain proportion of heterophilous nodes, challenging the homophily assumption of traditional GNNs and…

Machine Learning · Computer Science 2025-02-04 Jiajun Zhou , Shengbo Gong , Xuanze Chen , Chenxuan Xie , Shanqing Yu , Qi Xuan , Xiaoniu Yang

In recent years, graph neural networks (GNN) have achieved significant developments in a variety of graph analytical tasks. Nevertheless, GNN's superior performance will suffer from serious damage when the collected node features or…

Machine Learning · Computer Science 2023-09-07 Sichao Fu , Qinmu Peng , Yang He , Baokun Du , Xinge You

Given high-dimensional time series data (e.g., sensor data), how can we detect anomalous events, such as system faults and attacks? More challengingly, how can we do this in a way that captures complex inter-sensor relationships, and…

Machine Learning · Computer Science 2021-06-15 Ailin Deng , Bryan Hooi

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

Graph anomaly detection faces significant challenges due to the scarcity of reliable anomaly-labeled datasets, driving the development of unsupervised methods. Graph autoencoders (GAEs) have emerged as a dominant approach by reconstructing…

Machine Learning · Computer Science 2025-06-03 Chunyu Wei , Wenji Hu , Xingjia Hao , Yunhai Wang , Yueguo Chen , Bing Bai , Fei Wang

Graph Neural Networks (GNNs) are widely used on a variety of graph-based machine learning tasks. For node-level tasks, GNNs have strong power to model the homophily property of graphs (i.e., connected nodes are more similar) while their…

Machine Learning · Computer Science 2022-04-26 Lun Du , Xiaozhou Shi , Qiang Fu , Xiaojun Ma , Hengyu Liu , Shi Han , Dongmei Zhang

Graph neural networks (GNNs) have shown great ability in modeling graphs, however, their performance would significantly degrade when there are noisy edges connecting nodes from different classes. To alleviate negative effect of noisy edges…

Social and Information Networks · Computer Science 2023-09-15 Xiao Shen , Mengqiu Shao , Shirui Pan , Laurence T. Yang , Xi Zhou