Semi-supervised multi-label learning (SSMLL) involves learning a multi-label classifier from a small set of labeled data and a large set of unlabeled data. Label enhancement (LE), accounting for the relative importance of labels, has been effective in improving the performance of supervised multi-label learning models. Nevertheless, generating a robust SSMLL model with LE based on incomplete label information remains challenging. In this paper, we pioneer the idea of applying LE to SSMLL. First, we design a kNN aggregation-based method, aiming to assign pseudo-labels to unlabeled data and perform the LE process by aggregating label information from neighboring instances. Leveraging the topological structure of the feature space is an effective LE approach for training. However, LE, decoupled from the training process, lacks the dynamic feedback of the training model. To improve this, we incorporate a label propagation mechanism that iteratively optimizes the LE process with the guidance of the available label information. Moreover, we consider local label correlations according to local linear embedding to further enhance the generalization ability of the learning model. Extensive experiments demonstrate that the proposed approach can effectively recover latent label information, resulting in significant performance improvement in SSMLL.

Partial label learning (PLL) tackles scenarios where the unique ground-truth label of each sample is concealed within a candidate label set. Dimensionality reduction, considering labeling confidence estimation, has become a promising strategy to enhance the generalization performance of PLL models. However, current studies achieve dimensionality reduction, often relying on kNN-based labeling confidence estimation or disregarding potential labeling information. To address this issue, this paper proposes a novel Confidence-induced granular Partial label feature selection method using Dependency and Similarity (CPDS), which consists of two phases: Labeling Confidence Estimation (LCE) and Feature Selection (FS). For LCE, through granular ball computing, the feature space's similarity and the label space's correlation between the training data and the granular ball can be fused simultaneously, thereby effectively reconstructing more credible labeling confidence from candidate labels with more diverse semantic representation information. In the FS stage, by leveraging the LC with more diverse information, the proposed PLL neighborhood decision system further effectively combines feature dependency and label similarity to identify a feature subset with more discriminative capabilities, thereby achieving better performance for classification tasks. Among them, feature dependency effectively utilizes the dependency between neighborhoods and equivalence relations, while label similarity fully exploits the similarity between each sample and its neighbors. Extensive experiments show that CPDS significantly outperforms the compared approaches in most cases on nine controlled UCI datasets and five real-world datasets, demonstrating the superiority of the proposed method.