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Poster
Robust Semi-Supervised Learning when Not All Classes have Labels
Lan-Zhe Guo · Yi-Ge Zhang · Zhi-Fan Wu · Jie-Jing Shao · Yu-Feng Li

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Semi-supervised learning (SSL) provides a powerful framework for leveraging unlabeled data. Existing SSL typically requires all classes have labels. However, in many real-world applications, there may exist some classes that are difficult to label or newly occurred classes that cannot be labeled in time, resulting in there are unseen classes in unlabeled data. Unseen classes will be misclassified as seen classes, causing poor classification performance. The performance of seen classes is also harmed by the existence of unseen classes. This limits the practical and wider application of SSL. To address this problem, this paper proposes a new SSL approach that can classify not only seen classes but also unseen classes. Our approach consists of two modules: unseen class classification and learning pace synchronization. Specifically, we first enable the SSL methods to classify unseen classes by exploiting pairwise similarity between examples and then synchronize the learning pace between seen and unseen classes by proposing an adaptive threshold with distribution alignment. Extensive empirical results show our approach achieves significant performance improvement in both seen and unseen classes compared with previous studies.

Keywords: Semi-Supervised Learning · novel class discovery · robust
[ Paper]  [ Poster]  [ OpenReview] 

Author Information

Lan-Zhe Guo (Nanjing University)
Yi-Ge Zhang (Nanjing University)
Zhi-Fan Wu (Nanjing University)
Jie-Jing Shao (Nanjing University)
Yu-Feng Li (Nanjing University)

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