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Related papers: PIF: Anomaly detection via preference embedding

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We address the problem of detecting anomalies as samples that do not conform to structured patterns represented by low-dimensional manifolds. To this end, we conceive a general anomaly detection framework called Preference Isolation Forest…

Machine Learning · Computer Science 2025-09-19 Filippo Leveni , Luca Magri , Cesare Alippi , Giacomo Boracchi

Anomaly detection is a fundamental problem in domains such as healthcare, manufacturing, and cybersecurity. This thesis proposes new unsupervised methods for anomaly detection in both structured and streaming data settings. In the first…

Machine Learning · Computer Science 2025-05-20 Filippo Leveni

We focus on the problem of identifying samples in a set that do not conform to structured patterns represented by low-dimensional manifolds. An effective way to solve this problem is to embed data in a high dimensional space, called…

Machine Learning · Computer Science 2025-05-19 Filippo Leveni , Luca Magri , Cesare Alippi , Giacomo Boracchi

We present an extension to the model-free anomaly detection algorithm, Isolation Forest. This extension, named Extended Isolation Forest (EIF), resolves issues with assignment of anomaly score to given data points. We motivate the problem…

Machine Learning · Computer Science 2020-07-09 Sahand Hariri , Matias Carrasco Kind , Robert J. Brunner

We consider the problem of detecting anomalies in a large dataset. We propose a framework called Partial Identification which captures the intuition that anomalies are easy to distinguish from the overwhelming majority of points by…

Machine Learning · Computer Science 2019-12-10 Parikshit Gopalan , Vatsal Sharan , Udi Wieder

Compared to theoretical frameworks that assume equal sensitivity to deviations in all features of data, the theory of anomaly detection allowing for variable sensitivity across features is less developed. To the best of our knowledge, this…

Methodology · Statistics 2026-02-11 Illia Donhauzer

Isolation forest (iForest) has been emerging as arguably the most popular anomaly detector in recent years due to its general effectiveness across different benchmarks and strong scalability. Nevertheless, its linear axis-parallel isolation…

Machine Learning · Computer Science 2023-06-12 Hongzuo Xu , Guansong Pang , Yijie Wang , Yongjun Wang

The detection of anomalous behaviours is an emerging need in many applications, particularly in contexts where security and reliability are critical aspects. While the definition of anomaly strictly depends on the domain framework, it is…

Machine Learning · Computer Science 2022-07-11 Elisa Marcelli , Tommaso Barbariol , Gian Antonio Susto

From the identification of a drawback in the Isolation Forest (IF) algorithm that limits its use in the scope of anomaly detection, we propose two extensions that allow to firstly overcome the previously mention limitation and secondly to…

Machine Learning · Computer Science 2018-10-30 Pierre-François Marteau , Saeid Soheily-Khah , Nicolas Béchet

Anomaly detection is critical in various fields, including intrusion detection, health monitoring, fault diagnosis, and sensor network event detection. The isolation forest (or iForest) approach is a well-known technique for detecting…

Machine Learning · Computer Science 2021-10-06 Seemandhar Jain , Prarthi Jain , Abhishek Srivastava

Anomaly Detection is an unsupervised learning task aimed at detecting anomalous behaviours with respect to historical data. In particular, multivariate Anomaly Detection has an important role in many applications thanks to the capability of…

Machine Learning · Computer Science 2021-07-14 Mattia Carletti , Matteo Terzi , Gian Antonio Susto

Anomaly Detection (AD) is evolving through algorithms capable of identifying outliers in complex datasets. The Isolation Forest (IF), a pivotal AD technique, exhibits adaptability limitations and biases. This paper introduces the…

Machine Learning · Computer Science 2025-11-11 Alessio Arcudi , Alessandro Ferreri , Francesco Borsatti , Gian Antonio Susto

For the purpose of monitoring the behavior of complex infrastructures (e.g. aircrafts, transport or energy networks), high-rate sensors are deployed to capture multivariate data, generally unlabeled, in quasi continuous-time to detect…

Machine Learning · Statistics 2019-10-10 Guillaume Staerman , Pavlo Mozharovskyi , Stephan Clémençon , Florence d'Alché-Buc

In this paper, we propose DiFF-RF, an ensemble approach composed of random partitioning binary trees to detect point-wise and collective (as well as contextual) anomalies. Thanks to a distance-based paradigm used at the leaves of the trees,…

Machine Learning · Computer Science 2021-01-15 Pierre-Francois Marteau

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

Functional Isolation Forest (FIF) is a recent state-of-the-art Anomaly Detection (AD) algorithm designed for functional data. It relies on a tree partition procedure where an abnormality score is computed by projecting each curve…

Machine Learning · Statistics 2025-02-26 Marta Campi , Guillaume Staerman , Gareth W. Peters , Tomoko Matsui

Anomaly detectors are often used to produce a ranked list of statistical anomalies, which are examined by human analysts in order to extract the actual anomalies of interest. Unfortunately, in realworld applications, this process can be…

Machine Learning · Computer Science 2017-09-01 Shubhomoy Das , Weng-Keen Wong , Alan Fern , Thomas G. Dietterich , Md Amran Siddiqui

Anomaly detection is a longstanding and active research area that has many applications in domains such as finance, security, and manufacturing. However, the efficiency and performance of anomaly detection algorithms are challenged by the…

Machine Learning · Computer Science 2025-04-16 Yang Cao , Haolong Xiang , Hang Zhang , Ye Zhu , Kai Ming Ting

Recently, federated learning frameworks such as Python TestBed for Federated Learning Algorithms and MicroPython TestBed for Federated Learning Algorithms have emerged to tackle user privacy concerns and efficiency in embedded systems. Even…

Machine Learning · Computer Science 2025-09-05 Pavle Vasiljevic , Milica Matic , Miroslav Popovic

Isolation Forest (iForest) is an unsupervised anomaly detection algorithm designed to effectively detect anomalies under the assumption that anomalies are ``few and different." Various studies have aimed to enhance iForest, but the…

Machine Learning · Computer Science 2025-03-18 Hun Kang , Kyoungok Kim
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