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We propose a novel unsupervised outlier detection method based on Randomized Principal Component Analysis (PCA). Motivated by the performance of Randomized PCA (RPCA) Forest in approximate K-Nearest Neighbor (KNN) search, we develop a novel…

Machine Learning · Computer Science 2026-05-12 Muhammad Rajabinasab , Farhad Pakdaman , Moncef Gabbouj , Peter Schneider-Kamp , Arthur Zimek

Time series data occurs widely, and outlier detection is a fundamental problem in data mining, which has numerous applications. Existing autoencoder-based approaches deliver state-of-the-art performance on challenging real-world data but…

Machine Learning · Computer Science 2022-04-08 Tung Kieu , Bin Yang , Chenjuan Guo , Christian S. Jensen , Yan Zhao , Feiteng Huang , Kai Zheng

In the age of social computing, finding interesting network patterns or motifs is significant and critical for various areas such as decision intelligence, intrusion detection, medical diagnosis, social network analysis, fake news…

Social and Information Networks · Computer Science 2022-04-07 Shuo Yu , Feng Xia , Yuchen Sun , Tao Tang , Xiaoran Yan , Ivan Lee

Outlier explanation is the task of identifying a set of features that distinguish a sample from normal data, which is important for downstream (human) decision-making. Existing methods are based on beam search in the space of feature…

Machine Learning · Computer Science 2022-07-19 Stefan Lüdtke , Christian Bartelt , Heiner Stuckenschmidt

Aleatoric and Epistemic uncertainty have achieved recent attention in the literature as different sources from which uncertainty can emerge in stochastic modeling. Epistemic being intrinsic or model based notions of uncertainty, and…

Methodology · Statistics 2025-08-15 Ryan Warnick

Random projection is a common technique for designing algorithms in a variety of areas, including information retrieval, compressive sensing and measuring of outlyingness. In this work, the original random projection outlyingness measure is…

Signal Processing · Electrical Eng. & Systems 2021-08-02 Martin Bauw , Santiago Velasco-Forero , Jesus Angulo , Claude Adnet , Olivier Airiau

We study the change detection problem with an unknown post-change distribution. Under this constraint, the unknown change in the distribution of observations may occur in many ways without much structure on the observations, whereas, before…

Signal Processing · Electrical Eng. & Systems 2020-12-11 Deniz Sargun , C. Emre Koksal

Unsupervised representation learning has been extensively employed in anomaly detection, achieving impressive performance. Extracting valuable feature vectors that can remarkably improve the performance of anomaly detection are essential in…

Machine Learning · Computer Science 2022-04-26 Muhao Xu , Xueying Zhou , Xizhan Gao , WeiKai He , Sijie Niu

An ever-growing number of vulnerabilities are reported every day. Yet these vulnerabilities are not all the same; Some are more targeted than others. Correctly estimating the likelihood of a vulnerability being exploited is a critical task…

Cryptography and Security · Computer Science 2023-04-21 Hadi Eskandari , Michael Bewong , Sabih ur Rehman

The article describes a practical method for detecting outlier database connections in real-time. Outlier connections are detected with a specified level of confidence. The method is based on generalized security rules and a simple but…

Databases · Computer Science 2025-01-15 Leonid Rodniansky , Tania Butovsky , Mikhail Shpak

Pedestrian detection is a problem of considerable practical interest. Adding to the list of successful applications of deep learning methods to vision, we report state-of-the-art and competitive results on all major pedestrian datasets with…

Computer Vision and Pattern Recognition · Computer Science 2013-04-03 Pierre Sermanet , Koray Kavukcuoglu , Soumith Chintala , Yann LeCun

Shortcut learning, i.e., a model's reliance on undesired features not directly relevant to the task, is a major challenge that severely limits the applications of machine learning algorithms, particularly when deploying them to assist in…

Machine Learning · Computer Science 2025-06-17 Lukas Kuhn , Sari Sadiya , Jorg Schlotterer , Florian Buettner , Christin Seifert , Gemma Roig

In unsupervised ensemble learning, one obtains predictions from multiple sources or classifiers, yet without knowing the reliability and expertise of each source, and with no labeled data to assess it. The task is to combine these possibly…

Machine Learning · Computer Science 2016-02-24 Ariel Jaffe , Ethan Fetaya , Boaz Nadler , Tingting Jiang , Yuval Kluger

The study of networks has emerged in diverse disciplines as a means of analyzing complex relationship data. Beyond graph analysis tasks like graph query processing, link analysis, influence propagation, there has recently been some work in…

Social and Information Networks · Computer Science 2017-11-15 Supriya Pandhre , Manish Gupta , Vineeth N Balasubramanian

Often the challenge associated with tasks like fraud and spam detection is the lack of all likely patterns needed to train suitable supervised learning models. This problem accentuates when the fraudulent patterns are not only scarce, they…

Machine Learning · Computer Science 2019-05-08 Utkarsh Porwal , Smruthi Mukund

Most real-world IoT data analysis tasks, such as clustering and anomaly event detection, are unsupervised and highly susceptible to the presence of outliers. In addition to sporadic scattered outliers caused by factors such as faulty sensor…

Machine Learning · Computer Science 2026-03-16 Yiqun Zhang , Zexi Tan , Xiaopeng Luo , Yunlin Liu

An outlier is an observation or a data point that is far from rest of the data points in a given dataset or we can be said that an outlier is away from the center of mass of observations. Presence of outliers can skew statistical measures…

Machine Learning · Computer Science 2021-06-17 Amulya Agarwal , Nitin Gupta

This study proposes a risk pricing anomaly detection method for social network user portraits based on graph neural networks (GNNs), aiming to improve the ability to identify abnormal users in social network environments. In view of the…

Machine Learning · Computer Science 2025-03-26 Yiwei Zhang

Universal outlier hypothesis testing is studied in a sequential setting. Multiple observation sequences are collected, a small subset of which are outliers. A sequence is considered an outlier if the observations in that sequence are…

Statistics Theory · Mathematics 2014-11-27 Yun Li , Sirin Nitinawarat , Venugopal V. Veeravalli

A new technique for the detection of outliers in contingency tables is introduced. Outliers thereby are unexpected cell counts with respect to classical loglinear Poisson models. Subsets of cell counts called minimal patterns are defined,…

Computation · Statistics 2012-11-15 Sonja Kuhnt , Fabio Rapallo , André Rehage