EAAI Journal 2026 Journal Article
Number-agnostic decoupled class discovery for open-world semi-supervised learning
- Guanjia Zhang
- Weiwei Xing
- Xiaoyu Guo
- Yue Cheng
- Xiang Wei
- Zhengyang Zhao
Open-world semi-supervised learning aims to discriminate known and novel classes in unlabeled data within a semi-supervised learning paradigm. Except for a few methods, many clustering-based open-world semi-supervised learning methods rely on a predefined number of classes to recognize novel classes, which hampers the ability of the model to discover novel classes and decreases the generalization performance. Furthermore, the coupled training of supervised and unsupervised learning on a shared classifier accelerates the learning of labeled known classes, inevitably satisfying the supervised objective faster and leading to biased predictions. To address these challenges in open-world environments, we propose a number-agnostic decoupled class discovery approach, named NADCD. In NADCD, a semi-supervised information propagation clustering algorithm is proposed to adaptively estimate the number of classes and dynamically generate class prototypes. These prototypes are subsequently employed to facilitate the learning of discriminative representations across different samples. In addition, NADCD decouples the supervised and unsupervised training objectives by introducing an auxiliary bias-decoupling classifier on the representation encoder, thereby mitigating the bias inherent in the learned representations of novel classes. Extensive experimental results across different settings on three benchmark datasets demonstrate the effectiveness of NADCD. We will release the code at: https: //github. com/srxhlife/NADCD.