A Radon-Nikodým Perspective on Anomaly Detection: Theory and Implications

Fuente: arXiv
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Autori principali: Mehendale, Shlok, Challa, Aditya, Yedida, Rahul, Danda, Sravan, Sarkar, Santonu, Saha, Snehanshu
Natura: Preprint
Pubblicazione: 2025
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author Mehendale, Shlok
Challa, Aditya
Yedida, Rahul
Danda, Sravan
Sarkar, Santonu
Saha, Snehanshu
author_facet Mehendale, Shlok
Challa, Aditya
Yedida, Rahul
Danda, Sravan
Sarkar, Santonu
Saha, Snehanshu
contents Which principle underpins the design of an effective anomaly detection loss function? The answer lies in the concept of Radon-Nikodým theorem, a fundamental concept in measure theory. The key insight from this article is: Multiplying the vanilla loss function with the Radon-Nikodým derivative improves the performance across the board. We refer to this as RN-Loss. We prove this using the setting of PAC (Probably Approximately Correct) learnability. Depending on the context a Radon-Nikodým derivative takes different forms. In the simplest case of supervised anomaly detection, Radon-Nikodým derivative takes the form of a simple weighted loss. In the case of unsupervised anomaly detection (with distributional assumptions), Radon-Nikodým derivative takes the form of the popular cluster based local outlier factor. We evaluate our algorithm on 96 datasets, including univariate and multivariate data from diverse domains, including healthcare, cybersecurity, and finance. We show that RN-Derivative algorithms outperform state-of-the-art methods on 68% of Multivariate datasets (based on F1 scores) and also achieves peak F1-scores on 72% of time series (Univariate) datasets.
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id arxiv_https___arxiv_org_abs_2502_18002
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Radon-Nikodým Perspective on Anomaly Detection: Theory and Implications
Mehendale, Shlok
Challa, Aditya
Yedida, Rahul
Danda, Sravan
Sarkar, Santonu
Saha, Snehanshu
Machine Learning
Artificial Intelligence
Which principle underpins the design of an effective anomaly detection loss function? The answer lies in the concept of Radon-Nikodým theorem, a fundamental concept in measure theory. The key insight from this article is: Multiplying the vanilla loss function with the Radon-Nikodým derivative improves the performance across the board. We refer to this as RN-Loss. We prove this using the setting of PAC (Probably Approximately Correct) learnability. Depending on the context a Radon-Nikodým derivative takes different forms. In the simplest case of supervised anomaly detection, Radon-Nikodým derivative takes the form of a simple weighted loss. In the case of unsupervised anomaly detection (with distributional assumptions), Radon-Nikodým derivative takes the form of the popular cluster based local outlier factor. We evaluate our algorithm on 96 datasets, including univariate and multivariate data from diverse domains, including healthcare, cybersecurity, and finance. We show that RN-Derivative algorithms outperform state-of-the-art methods on 68% of Multivariate datasets (based on F1 scores) and also achieves peak F1-scores on 72% of time series (Univariate) datasets.
title A Radon-Nikodým Perspective on Anomaly Detection: Theory and Implications
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2502.18002