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Out-of-distribution (OoD) detection is a natural downstream task for deep generative models, due to their ability to learn the input probability distribution. There are mainly two classes of approaches for OoD detection using deep…

Machine Learning · Computer Science 2019-07-11 Yujia Huang , Sihui Dai , Tan Nguyen , Richard G. Baraniuk , Anima Anandkumar

Outlier detection tasks aim at discovering potential issues or opportunities and are widely used in cybersecurity, financial security, industrial inspection, etc. To date, thousands of outlier detection algorithms have been proposed.…

Machine Learning · Computer Science 2025-02-11 Qi Li

Anomaly detection on text-rich graphs is widely prevalent in real life, such as detecting incorrectly assigned academic papers to authors and detecting bots in social networks. The remarkable capabilities of large language models (LLMs)…

Computation and Language · Computer Science 2025-08-08 Yunhe Pang , Bo Chen , Fanjin Zhang , Yanghui Rao , Evgeny Kharlamov , Jie Tang

Detecting and rejecting unknown out-of-distribution (OOD) samples is critical for deployed neural networks to void unreliable predictions. In real-world scenarios, however, the efficacy of existing OOD detection methods is often impeded by…

Computer Vision and Pattern Recognition · Computer Science 2024-11-01 Kai Liu , Zhihang Fu , Sheng Jin , Chao Chen , Ze Chen , Rongxin Jiang , Fan Zhou , Yaowu Chen , Jieping Ye

Detecting intrusions in network traffic is a challenging task, particularly under limited supervision and constantly evolving attack patterns. While recent works have leveraged graph neural networks for network intrusion detection, they…

Machine Learning · Computer Science 2025-12-23 Lorenzo Guerra , Thomas Chapuis , Guillaume Duc , Pavlo Mozharovskyi , Van-Tam Nguyen

Out-of-distribution (OOD) generalization on graphs aims at dealing with scenarios where the test graph distribution differs from the training graph distributions. Compared to i.i.d. data like images, the OOD generalization problem on…

Machine Learning · Computer Science 2025-02-13 Song Wang , Zhen Tan , Yaochen Zhu , Chuxu Zhang , Jundong Li

Graph anomaly detection (GAD) is critical for identifying abnormal nodes in graph-structured data from diverse domains, including cybersecurity and social networks. The existing GAD methods often focus on the learning paradigms of…

Machine Learning · Computer Science 2026-02-24 Yixin Liu , Shiyuan Li , Yu Zheng , Qingfeng Chen , Chengqi Zhang , Philip S. Yu , Shirui Pan

Anomalies represent rare observations (e.g., data records or events) that deviate significantly from others. Over several decades, research on anomaly mining has received increasing interests due to the implications of these occurrences in…

Machine Learning · Computer Science 2022-04-21 Xiaoxiao Ma , Jia Wu , Shan Xue , Jian Yang , Chuan Zhou , Quan Z. Sheng , Hui Xiong , Leman Akoglu

Outlier detection refers to the identification of anomalous samples that deviate significantly from the distribution of normal data and has been extensively studied and used in a variety of practical tasks. However, most unsupervised…

Machine Learning · Computer Science 2025-01-07 Can Gao , Xiaofeng Tan , Jie Zhou , Weiping Ding , Witold Pedrycz

A key component of many graph neural networks (GNNs) is the pooling operation, which seeks to reduce the size of a graph while preserving important structural information. However, most existing graph pooling strategies rely on an…

Machine Learning · Computer Science 2023-10-17 Mahsa Mesgaran , A. Ben Hamza

A multitude of toxic online behaviors, ranging from network attacks to anonymous traffic and spam, have severely disrupted the smooth operation of networks. Due to the inherent sender-receiver nature of network behaviors, graph-based…

Machine Learning · Computer Science 2024-01-22 Ziqi Yuan , Haoyi Zhou , Tianyu Chen , Jianxin Li

The graph neural network (GNN) has demonstrated its superior performance in various applications. The working mechanism behind it, however, remains mysterious. GNN models are designed to learn effective representations for graph-structured…

Machine Learning · Computer Science 2022-06-10 Zepeng Zhang , Ziping Zhao

Cyberthreats are a permanent concern in our modern technological world. In the recent years, sophisticated traffic analysis techniques and anomaly detection (AD) algorithms have been employed to face the more and more subversive adversarial…

Machine Learning · Computer Science 2022-05-17 Paul Irofti , Andrei Pătraşcu , Andrei Iulian Hîji

Detecting a small number of outliers from a set of data observations is always challenging. This problem is more difficult in the setting of multiple network samples, where computing the anomalous degree of a network sample is generally not…

Artificial Intelligence · Computer Science 2016-10-04 Xuan-Hong Dang , Arlei Silva , Ambuj Singh , Ananthram Swami , Prithwish Basu

In real-world graphs, we often encounter missing feature situations where a few or the majority of node features, e.g., sensitive information, are missed. In such scenarios, directly utilizing Graph Neural Networks (GNNs) would yield…

Machine Learning · Computer Science 2025-08-05 Sukwon Yun , Xin Liu , Yunhak Oh , Junseok Lee , Tianlong Chen , Tsuyoshi Murata , Chanyoung Park

Graph anomaly detection on attributed networks has become a prevalent research topic due to its broad applications in many influential domains. In real-world scenarios, nodes and edges in attributed networks usually display distinct…

Social and Information Networks · Computer Science 2022-08-18 Shujie Yang , Binchi Zhang , Shangbin Feng , Zhaoxuan Tan , Qinghua Zheng , Jun Zhou , Minnan Luo

Zero-shot graph anomaly detection (GAD) has attracted increasing attention recent years, yet the heterogeneity of graph structures, features, and anomaly patterns across graphs make existing single GNN methods insufficiently expressive to…

Information Retrieval · Computer Science 2026-02-13 Haiyang Jiang , Tong Chen , Xinyi Gao , Guansong Pang , Quoc Viet Hung Nguyen , Hongzhi Yin

The inability of deep learning models to handle data drawn from unseen distributions has sparked much interest in unsupervised out-of-distribution (U-OOD) detection, as it is crucial for reliable deep learning models. Despite considerable…

Computer Vision and Pattern Recognition · Computer Science 2024-07-08 Lars Doorenbos , Raphael Sznitman , Pablo Márquez-Neila

The last few years have seen an increasing wave of attacks with serious economic and privacy damages, which evinces the need for accurate Network Intrusion Detection Systems (NIDS). Recent works propose the use of Machine Learning (ML)…

Cryptography and Security · Computer Science 2021-08-02 David Pujol-Perich , José Suárez-Varela , Albert Cabellos-Aparicio , Pere Barlet-Ros

Graph Anomaly Detection (GAD) is critical in security-sensitive domains, yet faces reliability challenges: miscalibrated confidence estimation (underconfidence in normal nodes, overconfidence in anomalies), adversarial vulnerability of…

Machine Learning · Computer Science 2025-04-04 Songran Bai , Xiaolong Zheng , Daniel Dajun Zeng