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Related papers: Detecting Anomalies Using Rotated Isolation Forest

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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

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

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

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

Isolation Forest (iForest) stands out as a widely-used unsupervised anomaly detector, primarily owing to its remarkable runtime efficiency and superior performance in large-scale tasks. Despite its widespread adoption, a theoretical…

Machine Learning · Computer Science 2026-01-28 Qin-Cheng Zheng , Shao-Qun Zhang , Shen-Huan Lyu , Yuan Jiang , Zhi-Hua Zhou

As cyber threats continue to evolve in sophistication and scale, the ability to detect anomalous network behavior has become critical for maintaining robust cybersecurity defenses. Modern cybersecurity systems face the overwhelming…

Machine Learning · Computer Science 2024-12-10 Christie Djidjev

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 (AD) focuses on identifying unusual behaviors in complex datasets. Machine Learning (ML) algorithms and Decision Support Systems (DSSs) provide effective solutions for AD, but detecting anomalies alone may not be enough,…

Machine Learning · Statistics 2024-10-10 Alessio Arcudi , Davide Frizzo , Chiara Masiero , Gian Antonio Susto

Random cut forest (RCF) algorithms have been developed for anomaly detection, particularly in time series data. The RCF algorithm is an improved version of the isolation forest (IF) algorithm. Unlike the IF algorithm, the RCF algorithm can…

Machine Learning · Computer Science 2024-01-10 Sijin Yeom , Jae-Hun Jung

Isolation forest or "iForest" is an intuitive and widely used algorithm for anomaly detection that follows a simple yet effective idea: in a given data distribution, if a threshold (split point) is selected uniformly at random within the…

Machine Learning · Statistics 2021-12-07 David Cortes

Unsupervised anomaly detection tackles the problem of finding anomalies inside datasets without the labels availability; since data tagging is typically hard or expensive to obtain, such approaches have seen huge applicability in recent…

Machine Learning · Computer Science 2021-12-01 Tommaso Barbariol , Gian Antonio Susto

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

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 anomaly detection is widely used in transaction fraud detection where labels are scarce. Isolation Forest (IF) is among the most popular classical methods due to its scalability and ease of deployment. We propose SilIF, an…

Machine Learning · Computer Science 2026-05-27 Venkatakrishnan Gopalakrishnan

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

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 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

In this paper, the mathematical analysis of the Isolation Random Forest Method (IRF Method) for anomaly detection is presented. We show that the IRF space can be endowed with a probability induced by the Isolation Tree algorithm (iTree). In…

Methodology · Statistics 2022-05-05 Fernando A. Morales , Jorge M. Ramírez , Edgar A. Ramos

Anomaly detection plays an increasingly important role in various fields for critical tasks such as intrusion detection in cybersecurity, financial risk detection, and human health monitoring. A variety of anomaly detection methods have…

Machine Learning · Computer Science 2023-06-26 Haolong Xiang , Xuyun Zhang , Hongsheng Hu , Lianyong Qi , Wanchun Dou , Mark Dras , Amin Beheshti , Xiaolong Xu
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