Leveraging Label Proportion Prior for Class-Imbalanced Semi-Supervised Learning

Fuente: arXiv
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Main Authors: Akiba, Kohki, Matsuo, Shinnosuke, Harada, Shota, Bise, Ryoma
Format: Preprint
Published: 2026
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author Akiba, Kohki
Matsuo, Shinnosuke
Harada, Shota
Bise, Ryoma
author_facet Akiba, Kohki
Matsuo, Shinnosuke
Harada, Shota
Bise, Ryoma
contents Semi-supervised learning (SSL) often suffers under class imbalance, where pseudo-labeling amplifies majority bias and suppresses minority performance. We address this issue with a lightweight framework that, to our knowledge, is the first to introduce Proportion Loss from learning from label proportions (LLP) into SSL as a regularization term. Proportion Loss aligns model predictions with the global class distribution, mitigating bias across both majority and minority classes. To further stabilize training, we formulate a stochastic variant that accounts for fluctuations in mini-batch composition. Experiments on the Long-tailed CIFAR-10 benchmark show that integrating Proportion Loss into FixMatch and ReMixMatch consistently improves performance over the baselines across imbalance severities and label ratios, and achieves competitive or superior results compared to existing CISSL methods, particularly under scarce-label conditions.
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id arxiv_https___arxiv_org_abs_2603_02957
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publishDate 2026
record_format arxiv
spellingShingle Leveraging Label Proportion Prior for Class-Imbalanced Semi-Supervised Learning
Akiba, Kohki
Matsuo, Shinnosuke
Harada, Shota
Bise, Ryoma
Machine Learning
Computer Vision and Pattern Recognition
Semi-supervised learning (SSL) often suffers under class imbalance, where pseudo-labeling amplifies majority bias and suppresses minority performance. We address this issue with a lightweight framework that, to our knowledge, is the first to introduce Proportion Loss from learning from label proportions (LLP) into SSL as a regularization term. Proportion Loss aligns model predictions with the global class distribution, mitigating bias across both majority and minority classes. To further stabilize training, we formulate a stochastic variant that accounts for fluctuations in mini-batch composition. Experiments on the Long-tailed CIFAR-10 benchmark show that integrating Proportion Loss into FixMatch and ReMixMatch consistently improves performance over the baselines across imbalance severities and label ratios, and achieves competitive or superior results compared to existing CISSL methods, particularly under scarce-label conditions.
title Leveraging Label Proportion Prior for Class-Imbalanced Semi-Supervised Learning
topic Machine Learning
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.02957