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Graph neural networks (GNNs) have shown advantages in graph-based analysis tasks. However, most existing methods have the homogeneity assumption and show poor performance on heterophilic graphs, where the linked nodes have dissimilar…

Machine Learning · Computer Science 2024-04-16 Tianhao Peng , Wenjun Wu , Haitao Yuan , Zhifeng Bao , Zhao Pengrui , Xin Yu , Xuetao Lin , Yu Liang , Yanjun Pu

Anomaly detection (AD) plays a crucial role in time series applications, primarily because time series data is employed across real-world scenarios. Detecting anomalies poses significant challenges since anomalies take diverse forms making…

Machine Learning · Computer Science 2025-01-03 Jihan Ghanim , Mariette Awad

Anomaly detection or more generally outliers detection is one of the most popular and challenging subject in theoretical and applied machine learning. The main challenge is that in general we have access to very few labeled data or no…

Machine Learning · Computer Science 2023-05-31 Mansour Zoubeirou A Mayaki , Michel Riveill

Unsupervised GAD methods assume the lack of anomaly labels, i.e., whether a node is anomalous or not. One common observation we made from previous unsupervised methods is that they not only assume the absence of such anomaly labels, but…

Machine Learning · Computer Science 2023-08-24 Junghoon Kim , Yeonjun In , Kanghoon Yoon , Junmo Lee , Chanyoung Park

With the rapid growth of graph-structured data in critical domains, unsupervised graph-level anomaly detection (UGAD) has become a pivotal task. UGAD seeks to identify entire graphs that deviate from normal behavioral patterns. However,…

Machine Learning · Computer Science 2025-11-07 Qingfeng Chen , Haojin Zeng , Jingyi Jie , Shichao Zhang , Debo Cheng

We study the problem of semi-supervised anomaly detection with domain adaptation. Given a set of normal data from a source domain and a limited amount of normal examples from a target domain, the goal is to have a well-performing anomaly…

Machine Learning · Computer Science 2020-06-09 Ziyi Yang , Iman Soltani Bozchalooi , Eric Darve

Graph anomaly detection (GAD), which aims to identify nodes in a graph that significantly deviate from normal patterns, plays a crucial role in broad application domains. However, existing GAD methods are one-model-for-one-dataset…

Machine Learning · Computer Science 2025-06-10 Chaoxi Niu , Hezhe Qiao , Changlu Chen , Ling Chen , Guansong Pang

Dynamic graph anomaly detection (DGAD) is critical for many real-world applications but remains challenging due to the scarcity of labeled anomalies. Existing methods are either unsupervised or semi-supervised: unsupervised methods avoid…

Machine Learning · Computer Science 2026-02-24 Yuxing Tian , Yiyan Qi , Fengran Mo , Weixu Zhang , Jian Guo , Jian-Yun Nie

Graph anomaly detection (GAD) has achieved success and has been widely applied in various domains, such as fraud detection, cybersecurity, finance security, and biochemistry. However, existing graph anomaly detection algorithms focus on…

Machine Learning · Computer Science 2023-08-03 Xing Ai , Jialong Zhou , Yulin Zhu , Gaolei Li , Tomasz P. Michalak , Xiapu Luo , Kai Zhou

We propose a simple yet effective method for detecting anomalous instances on an attribute graph with label information of a small number of instances. Although with standard anomaly detection methods it is usually assumed that instances…

Machine Learning · Statistics 2020-02-28 Atsutoshi Kumagai , Tomoharu Iwata , Yasuhiro Fujiwara

Graph anomaly detection aims to identify unusual patterns in graph-based data, with wide applications in fields such as web security and financial fraud detection. Existing methods typically rely on contrastive learning, assuming that a…

Machine Learning · Computer Science 2025-05-26 Di Jin , Jingyi Cao , Xiaobao Wang , Bingdao Feng , Dongxiao He , Longbiao Wang , Jianwu Dang

Graph Anomaly Detection (GAD) plays a vital role in various data mining applications such as e-commerce fraud prevention and malicious user detection. Recently, Graph Neural Network (GNN) based approach has demonstrated great effectiveness…

Machine Learning · Computer Science 2025-03-18 Hang Ni , Jindong Han , Nengjun Zhu , Hao Liu

Anomaly detection on dynamic graphs refers to detecting entities whose behaviors obviously deviate from the norms observed within graphs and their temporal information. This field has drawn increasing attention due to its application in…

Machine Learning · Computer Science 2023-10-26 Shiqi Lou , Qingyue Zhang , Shujie Yang , Yuyang Tian , Zhaoxuan Tan , Minnan Luo

Anomaly detection in time series has been widely researched and has important practical applications. In recent years, anomaly detection algorithms are mostly based on deep-learning generative models and use the reconstruction error to…

Machine Learning · Computer Science 2020-10-15 Chunkai Zhang , Wei Zuo , Xuan Wang

Weakly supervised graph anomaly detection aims to unveil unusual graph instances, e.g., nodes, whose behaviors significantly differ from normal ones, given only a limited number of annotated anomalies and abundant unlabeled samples. A major…

Machine Learning · Computer Science 2026-05-13 Yingjie Zhou , Yuqin Xie , Fanxing Liu , Dongjin Song , Ce Zhu , Lingqiao Liu

Semi-supervised Anomaly Detection (AD) is a kind of data mining task which aims at learning features from partially-labeled datasets to help detect outliers. In this paper, we classify existing semi-supervised AD methods into two…

Machine Learning · Computer Science 2022-10-27 Chao Chen , Dawei Wang , Feng Mao , Zongzhang Zhang , Yang Yu

Unsupervised graph representation learning aims to learn low-dimensional node embeddings without supervision while preserving graph topological structures and node attributive features. Previous graph neural networks (GNN) require a large…

Machine Learning · Computer Science 2020-09-04 Yanqiao Zhu , Yichen Xu , Feng Yu , Shu Wu , Liang Wang

The goal of anomaly detection is to identify anomalous samples from normal ones. In this paper, a small number of anomalies are assumed to be available at the training stage, but they are assumed to be collected only from several anomaly…

Machine Learning · Computer Science 2022-05-03 Bowen Tian , Qinliang Su , Jian Yin

Graph-level anomaly detection aims to identify anomalous graphs or subgraphs within graph datasets, playing a vital role in various fields such as fraud detection, review classification, and biochemistry. While Graph Neural Networks (GNNs)…

Machine Learning · Computer Science 2025-10-10 Liting Li , Yumeng Wang , Yueheng Sun

Anomaly detection is a task that recognizes whether an input sample is included in the distribution of a target normal class or an anomaly class. Conventional generative adversarial network (GAN)-based methods utilize an entire image…

Computer Vision and Pattern Recognition · Computer Science 2021-04-01 Jou Won Song , Kyeongbo Kong , Ye In Park , Suk-Ju Kang