Feature dynamics have emerged as a critical topic about open-environment learning due to the instability of feature availability. While traditional feature evolution targets single-label tasks, multi-label learning is essential to accommodate the exploding annotation spaces. However, multi-label classification with incremental and decremental features is a crucial yet underexplored problem, which poses the challenge of preserving feature representations and label correlations from historical instances and simultaneously adapting to newly arriving streaming data. To address these issues, we propose a two-stage, one-pass learning approach termed MLID. It attempts to compress the informative content of vanished features into the domain of survived ones, facilitate the propagation of label dependencies via low-rank regularization of the classifier, and incorporate augmented features to construct an adaptive classification mechanism. Besides, we design optimization strategies for each stage and provide theoretical guarantees of convergence. Moreover, we establish the generalization error bound of MLID and demonstrate that the compactness of the trace norm and the reuse of models based on effective features can enhance the generalization performance. Finally, we extend it to multi-shot case and extensive experimental results validate the superiority of our MLID.

Multi-view multi-label learning has become a research focus for describing objects with rich expressions and annotations. However, real-world data often contains numerous unlabeled instances, due to the high cost and technical limitations of manual labeling. This crucial problem involves three main challenges: i) How to extract advanced semantics from available views? ii) How to build a refined classification framework with limited labeled space? iii) How to provide more high-quality supervisory information? To address these problems, we propose a Semi-Supervised Multi-View Multi-Label Learning Method with View-Specific Transformer and Enhanced Pseudo-Label named SMVTEP. Specifically, Generative Adversarial Networks are employed to extract informative shared and specific representations and their consistency and distinctiveness are ensured through the adversarial mechanism and information theory based contrastive learning. Then we build specific classifiers for each extracted feature and apply instance-level manifold constraints to reduce bias across classifiers. Moreover, we design a transformer-style fusion approach that simultaneously captures the imbalance of expressive power among views, mapping effects on specific labels, and label dependencies by incorporating confidence scores and category semantics into the self-attention mechanism. Furthermore, after using Mixup for data augmentation, category-enhanced pseudo-labels are leveraged to improve the reliability of additional annotations by aligning the label distribution of unlabeled samples with the true distribution. Finally, extensive experimental results validate the effectiveness of SMVTEP against state-of-the-art methods.

Due to the explosive growth in data sources and label categories, multi-view multi-label learning has garnered widespread attention. However, multi-view multi-label data often exhibits incomplete features and a huge number of unlabeled instances, due to the technical limitations and high cost of manual labeling in practice. Learning for such simultaneous missing of view features and labels is crucial but rarely studied, particularly when the labeled samples are limited. In this paper, we tackle this problem by proposing a novel Deep Incomplete Multi-View Semi-Supervised Multi-Label Learning method (DIMvSML). Specifically, to improve high-level representations of missing features, deep graph network is firstly employed to recover the feature information with structural similarity relations. Meanwhile, we design the structure-specific deep feature extractors to obtain discriminative information and preserve the cross-view consistency for the recovered data with instance-level contrastive loss. Furthermore, to eliminate the bias of the estimate of the risk that the semi-supervised multi-label methods minimise, we design a safe estimate framework with an unbiased loss and improve its empirical performance by using pseudo-labels of unlabeled data. Besides, we provide both the theoretical proof of better estimate variance and the intuitive explanation of our debiased framework. Finally, extensive experimental results on public datasets validate the superiority of DIMvSML compared with state-of-the-art methods.