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Test-Time Learning for Outlier Detection




TekijätYang, Jiawei; Chen, Jingdong; Rahardja, Susanto

KustantajaInstitute of Electrical and Electronics Engineers (IEEE)

Julkaisuvuosi2026

Lehti: IEEE Transactions on Knowledge and Data Engineering

ISSN1041-4347

eISSN2326-3865

DOIhttps://doi.org/10.1109/TKDE.2026.3689274

Julkaisun avoimuus kirjaamishetkelläEi avoimesti saatavilla

Julkaisukanavan avoimuus Osittain avoin julkaisukanava

Verkko-osoitehttps://doi.org/10.1109/tkde.2026.3689274

Rinnakkaistallenteen osoitehttps://research.utu.fi/converis/portal/detail/Publication/526499973

Rinnakkaistallenteen lisenssiAll rights reserved

Rinnakkaistallennetun julkaisun versioFinal draft


Tiivistelmä
In this work, the concept of test-time learning is presented, wherein Machine-Learning (ML) models are constructed by involving unlabeled test samples. Based on this concept, we propose a method called Local Augment (LA) designed to improve the performance of trained outlier detectors at the prediction stage without altering the trained models or accessing the training data. LA operates under the only assumption that the model should produce similar outputs for similar inputs, implying that the prediction of a given sample can be enhanced by the predictions for its similar samples. Specifically, LA boosts outlier detection performance during prediction by fusing the outlier score of a given sample with the scores of synthetically neighboring samples generated by adding random perturbations to the given sample. This simple method demonstrates an average improvement of about +0.04 Area Under the Receiver Operating Characteristic curve (AUROC) across 26 real-world datasets for all 14 tested detectors. Notably, this represents the pioneering work of enhancing ML models during the prediction stage without the need to modify the trained models or access the training dataset. This work opens up new possibilities for addressing existing bottleneck problems in various ML tasks beyond outlier detection in diverse domains.


Avainsanat:
LAlocal augmentoutlier detectiontest-time learning

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Julkaisussa olevat rahoitustiedot
This work was supported in part by the National Key Research and Development Program of China, STI 2030 Major Projects under Grant 2021ZD0201502. This project has received funding from the European Union’s Horizon Europe research and innovation programme under Marie Sklodowska-Curie grant agreement no [101126611].


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