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Graph Neural Networks (GNNs) are proposed without considering the agnostic distribution shifts between training and testing graphs, inducing the degeneration of the generalization ability of GNNs on Out-Of-Distribution (OOD) settings. The…

Machine Learning · Computer Science 2024-03-12 Shaohua Fan , Xiao Wang , Chuan Shi , Peng Cui , Bai Wang

Outlier, or anomaly, detection is essential for optimal performance of machine learning methods and statistical predictive models. It is not just a technical step in a data cleaning process but a key topic in many fields such as fraudulent…

Machine Learning · Computer Science 2020-02-19 O. Ramos Terrades , A. Berenguel , D. Gil

We propose two new outlier detection methods, for identifying and classifying different types of outliers in (big) functional data sets. The proposed methods are based on an existing method called Massive Unsupervised Outlier Detection…

Methodology · Statistics 2021-10-15 Oluwasegun Taiwo Ojo , Antonio Fernández Anta , Rosa E. Lillo , Carlo Sguera

Recent studies have revealed that GNNs are highly susceptible to multiple adversarial attacks. Among these, graph backdoor attacks pose one of the most prominent threats, where attackers cause models to misclassify by learning the…

Cryptography and Security · Computer Science 2024-10-21 Hao Sui , Bing Chen , Jiale Zhang , Chengcheng Zhu , Di Wu , Qinghua Lu , Guodong Long

To deal with distribution shifts in graph data, various graph out-of-distribution (OOD) generalization techniques have been recently proposed. These methods often employ a two-step strategy that first creates augmented environments and…

Machine Learning · Computer Science 2025-01-09 Song Wang , Xiaodong Yang , Rashidul Islam , Huiyuan Chen , Minghua Xu , Jundong Li , Yiwei Cai

The open-world test dataset is often mixed with out-of-distribution (OOD) samples, where the deployed models will struggle to make accurate predictions. Traditional detection methods need to trade off OOD detection and in-distribution (ID)…

Machine Learning · Computer Science 2024-04-25 Xu Shen , Yili Wang , Kaixiong Zhou , Shirui Pan , Xin Wang

Graph Out-of-Distribution (OOD) detection aims to identify whether a test graph deviates from the distribution of graphs observed during training, which is critical for ensuring the reliability of Graph Neural Networks (GNNs) when deployed…

Machine Learning · Computer Science 2026-02-20 Luzhi Wang , Xuanshuo Fu , He Zhang , Chuang Liu , Xiaobao Wang , Hongbo Liu

Graph Neural Network (GNN) has demonstrated extraordinary performance in classifying graph properties. However, due to the selection bias of training and testing data (e.g., training on small graphs and testing on large graphs, or training…

Machine Learning · Computer Science 2023-08-17 Bin Lu , Xiaoying Gan , Ze Zhao , Shiyu Liang , Luoyi Fu , Xinbing Wang , Chenghu Zhou

Graph Anomaly Detection (GAD) is increasingly shifting to Generalist GAD (GGAD) for cross-domain "one-for-all" detection, but existing GGAD methods predominantly rely on the neighbor consistency principle, falling into the…

Machine Learning · Computer Science 2026-05-21 Kaifeng Wei , Teng Liu , Liang Dong , Xiubo Liang , Yuke Li

Modern in-vehicle networks face various cyber threats due to the lack of encryption and authentication in the Controller Area Network (CAN). To address this security issue, this paper presents GUARD-CAN, an anomaly detection framework that…

Cryptography and Security · Computer Science 2025-07-30 Hyeong Seon Kim , Huy Kang Kim

Outlier detection refers to the identification of data points that deviate from a general data distribution. Existing unsupervised approaches often suffer from high computational cost, complex hyperparameter tuning, and limited…

Machine Learning · Computer Science 2022-08-26 Zheng Li , Yue Zhao , Xiyang Hu , Nicola Botta , Cezar Ionescu , George H. Chen

The problem of out-of-distribution detection for graph classification is far from being solved. The existing models tend to be overconfident about OOD examples or completely ignore the detection task. In this work, we consider this problem…

Machine Learning · Computer Science 2022-06-23 Gleb Bazhenov , Sergei Ivanov , Maxim Panov , Alexey Zaytsev , Evgeny Burnaev

Attributed network embedding has received much interest from the research community as most of the networks come with some content in each node, which is also known as node attributes. Existing attributed network approaches work well when…

Social and Information Networks · Computer Science 2018-11-20 Sambaran Bandyopadhyay , Lokesh N , M. N. Murty

Addressing the Out-of-Distribution (OoD) segmentation task is a prerequisite for perception systems operating in an open-world environment. Large foundational models are frequently used in downstream tasks, however, their potential for OoD…

Computer Vision and Pattern Recognition · Computer Science 2024-09-11 Nazir Nayal , Youssef Shoeb , Fatma Güney

Outlier detection is one of the most important processes taken to create good, reliable data in machine learning. The most methods of outlier detection leverage an auxiliary reconstruction task by assuming that outliers are more difficult…

Computer Vision and Pattern Recognition · Computer Science 2022-11-23 Ning Huyan , Dou Quan , Xiangrong Zhang , Xuefeng Liang , Jocelyn Chanussot , Licheng Jiao

Distribution shifts on graphs -- the data distribution discrepancies between training and testing a graph machine learning model, are often ubiquitous and unavoidable in real-world scenarios. Such shifts may severely deteriorate the…

Machine Learning · Computer Science 2024-02-20 Shuhan Liu , Kaize Ding

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

We study the problem of lifelong graph learning in an open-world scenario, where a model needs to deal with new tasks and potentially unknown classes. We utilize Out-of-Distribution (OOD) detection methods to recognize new classes and adapt…

Machine Learning · Computer Science 2023-10-20 Marcel Hoffmann , Lukas Galke , Ansgar Scherp

While Transformers have revolutionized machine learning on various data, existing Transformers for temporal graphs face limitations in (1) restricted receptive fields, (2) overhead of subgraph extraction, and (3) suboptimal generalization…

Machine Learning · Computer Science 2024-12-03 Kay Liu , Jiahao Ding , MohamadAli Torkamani , Philip S. Yu

Graph neural networks (GNNs) have been demonstrated to perform well in graph representation learning, but always lacking in generalization capability when tackling out-of-distribution (OOD) data. Graph invariant learning methods, backed by…

Machine Learning · Computer Science 2023-12-19 Tianrui Jia , Haoyang Li , Cheng Yang , Tao Tao , Chuan Shi