USE: Uncertainty Structure Estimation for Robust Semi-Supervised Learning

Fuente: arXiv
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Main Authors: Chen, Tsao-Lun, Liu, Chien-Liang, Hsu, Tzu-Ming Harry, Wu, Tai-Hsien, Fu, Chi-Cheng, Chou, Han-Yi E., Su, Shun-Feng
Format: Preprint
Published: 2026
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author Chen, Tsao-Lun
Liu, Chien-Liang
Hsu, Tzu-Ming Harry
Wu, Tai-Hsien
Fu, Chi-Cheng
Chou, Han-Yi E.
Su, Shun-Feng
author_facet Chen, Tsao-Lun
Liu, Chien-Liang
Hsu, Tzu-Ming Harry
Wu, Tai-Hsien
Fu, Chi-Cheng
Chou, Han-Yi E.
Su, Shun-Feng
contents In this study, a novel idea, Uncertainty Structure Estimation (USE), a lightweight, algorithm-agnostic procedure that emphasizes the often-overlooked role of unlabeled data quality is introduced for Semi-supervised learning (SSL). SSL has achieved impressive progress, but its reliability in deployment is limited by the quality of the unlabeled pool. In practice, unlabeled data are almost always contaminated by out-of-distribution (OOD) samples, where both near-OOD and far-OOD can negatively affect performance in different ways. We argue that the bottleneck does not lie in algorithmic design, but rather in the absence of principled mechanisms to assess and curate the quality of unlabeled data. The proposed USE trains a proxy model on the labeled set to compute entropy scores for unlabeled samples, and then derives a threshold, via statistical comparison against a reference distribution, that separates informative (structured) from uninformative (structureless) samples. This enables assessment as a preprocessing step, removing uninformative or harmful unlabeled data before SSL training begins. Through extensive experiments on imaging (CIFAR-100) and NLP (Yelp Review) data, it is evident that USE consistently improves accuracy and robustness under varying levels of OOD contamination. Thus, it can be concluded that the proposed approach reframes unlabeled data quality control as a structural assessment problem, and considers it as a necessary component for reliable and efficient SSL in realistic mixed-distribution environments.
format Preprint
id arxiv_https___arxiv_org_abs_2603_00404
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle USE: Uncertainty Structure Estimation for Robust Semi-Supervised Learning
Chen, Tsao-Lun
Liu, Chien-Liang
Hsu, Tzu-Ming Harry
Wu, Tai-Hsien
Fu, Chi-Cheng
Chou, Han-Yi E.
Su, Shun-Feng
Machine Learning
Artificial Intelligence
In this study, a novel idea, Uncertainty Structure Estimation (USE), a lightweight, algorithm-agnostic procedure that emphasizes the often-overlooked role of unlabeled data quality is introduced for Semi-supervised learning (SSL). SSL has achieved impressive progress, but its reliability in deployment is limited by the quality of the unlabeled pool. In practice, unlabeled data are almost always contaminated by out-of-distribution (OOD) samples, where both near-OOD and far-OOD can negatively affect performance in different ways. We argue that the bottleneck does not lie in algorithmic design, but rather in the absence of principled mechanisms to assess and curate the quality of unlabeled data. The proposed USE trains a proxy model on the labeled set to compute entropy scores for unlabeled samples, and then derives a threshold, via statistical comparison against a reference distribution, that separates informative (structured) from uninformative (structureless) samples. This enables assessment as a preprocessing step, removing uninformative or harmful unlabeled data before SSL training begins. Through extensive experiments on imaging (CIFAR-100) and NLP (Yelp Review) data, it is evident that USE consistently improves accuracy and robustness under varying levels of OOD contamination. Thus, it can be concluded that the proposed approach reframes unlabeled data quality control as a structural assessment problem, and considers it as a necessary component for reliable and efficient SSL in realistic mixed-distribution environments.
title USE: Uncertainty Structure Estimation for Robust Semi-Supervised Learning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2603.00404