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Among the many challenges posed by the huge data volumes produced by the new generation of astronomical instruments there is also the search for rare and peculiar objects. Unsupervised outlier detection algorithms may provide a viable…

Instrumentation and Methods for Astrophysics · Physics 2021-05-12 Lars Doorenbos , Stefano Cavuoti , Massimo Brescia , Antonio D'Isanto , Giuseppe Longo

This paper proposes an extension of Random Projection Depth (RPD) to cope with multiple modalities and non-convexity on data clouds. In the framework of the proposed method, the RPD is computed in a reproducing kernel Hilbert space. With…

Machine Learning · Statistics 2023-09-07 Akira Tamamori

Outlier detection in high-dimensional data is a challenging yet important task, as it has applications in, e.g., fraud detection and quality control. State-of-the-art density-based algorithms perform well because they 1) take the local…

Artificial Intelligence · Computer Science 2016-11-02 Bas van Stein , Matthijs van Leeuwen , Thomas Bäck

We study the classic $k$-means/median clustering, which are fundamental problems in unsupervised learning, in the setting where data are partitioned across multiple sites, and where we are allowed to discard a small portion of the data by…

Distributed, Parallel, and Cluster Computing · Computer Science 2018-10-12 Jiecao Chen , Erfan Sadeqi Azer , Qin Zhang

Observations in data which are significantly different from its neighbouring points but cannot be classified as noise are known as anomalies or outliers. These anomalies are a cause of concern and a timely warning about their presence could…

Applications · Statistics 2020-06-09 Krishnam Kapoor

We introduce an online outlier detection algorithm to detect outliers in a sequentially observed data stream. For this purpose, we use a two-stage filtering and hedging approach. In the first stage, we construct a multi-modal probability…

Machine Learning · Computer Science 2018-03-13 Mohammadreza Mohaghegh Neyshabouri , Suleyman Serdar Kozat

The problem of outlier detection is extremely challenging in many domains such as text, in which the attribute values are typically non-negative, and most values are zero. In such cases, it often becomes difficult to separate the outliers…

Information Retrieval · Computer Science 2017-01-06 Ramakrishnan Kannan , Hyenkyun Woo , Charu C. Aggarwal , Haesun Park

Outlier detection is an essential capability in safety-critical applications of supervised visual recognition. Most of the existing methods deliver best results by encouraging standard closed-set models to produce low-confidence predictions…

Computer Vision and Pattern Recognition · Computer Science 2024-09-10 Anja Delić , Matej Grcić , Siniša Šegvić

Rare data in a large-scale database are called outliers that reveal significant information in the real world. The subspace-based outlier detection is regarded as a feasible approach in very high dimensional space. However, the outliers…

Artificial Intelligence · Computer Science 2014-05-06 Zhana Bao

Distributional data analysis, concerned with statistical analysis and modeling for data objects consisting of random probability density functions (PDFs) in the framework of functional data analysis (FDA), has received considerable interest…

Methodology · Statistics 2021-10-05 Xinyi Lei , Zhicheng Chen , Hui Li

As language models become more general purpose, increased attention needs to be paid to detecting out-of-distribution (OOD) instances, i.e., those not belonging to any of the distributions seen during training. Existing methods for…

Machine Learning · Computer Science 2024-07-19 Aryan Gulati , Xingjian Dong , Carlos Hurtado , Sarath Shekkizhar , Swabha Swayamdipta , Antonio Ortega

In recent years, there have been many practical applications of anomaly detection such as in predictive maintenance, detection of credit fraud, network intrusion, and system failure. The goal of anomaly detection is to identify in the test…

Applications · Statistics 2020-06-12 Zekun Xu , Deovrat Kakde , Arin Chaudhuri

Outlier detection refers to the identification of rare items that are deviant from the general data distribution. Existing approaches suffer from high computational complexity, low predictive capability, and limited interpretability. As a…

Machine Learning · Statistics 2022-01-04 Zheng Li , Yue Zhao , Nicola Botta , Cezar Ionescu , Xiyang Hu

Out-of-Distribution (OoD) detection is important for building safe artificial intelligence systems. However, current OoD detection methods still cannot meet the performance requirements for practical deployment. In this paper, we propose a…

Machine Learning · Statistics 2020-12-18 Haiwen Huang , Zhihan Li , Lulu Wang , Sishuo Chen , Bin Dong , Xinyu Zhou

We present a novel method for detecting outliers in astronomical time series based on the combination of a deep neural network and a k-nearest neighbor algorithm with the aim of identifying and removing problematic epochs in the light…

Instrumentation and Methods for Astrophysics · Physics 2024-07-24 Stefano Cavuoti , Demetra De Cicco , Lars Doorenbos , Massimo Brescia , Olena Torbaniuk , Giuseppe Longo , Maurizio Paolillo

Functional data covers a wide range of data types. They all have in common that the observed objects are functions of of a univariate argument (e.g. time or wavelength) or a multivariate argument (say, a spatial position). These functions…

Methodology · Statistics 2021-01-13 Peter J. Rousseeuw , Jakob Raymaekers , Mia Hubert

In an industrial context, the activity of sensors is recorded at a high frequency. A challenge is to automatically detect abnormal measurement behavior. Considering the sensor measures as functional data, the problem can be formulated as…

Statistics Theory · Mathematics 2022-03-09 Martial Amovin-Assagba , Irène Gannaz , Julien Jacques

With the development of data-monitoring techniques in various fields of science, multivariate functional data are often observed. Consequently, an increasing number of methods have appeared to extend the general summary statistics of…

Methodology · Statistics 2020-12-09 Zonghui Yao , Wenlin Dai , Marc G. Genton

Outlying observations, which significantly deviate from other measurements, may distort the conclusions of data analysis. Therefore, identifying outliers is one of the important problems that should be solved to obtain reliable results.…

Computation · Statistics 2014-05-01 Soo-Heang Eo , Seung-Mo Hong , HyungJun Cho

We discuss a general framework for recovering edges in piecewise smooth functions with finitely many jump discontinuities, where $[f](x):=f(x+)-f(x-) \neq 0$. Our approach is based on two main aspects--localization using appropriate…

Numerical Analysis · Mathematics 2025-10-20 Anne Gelb , Eitan Tadmor