Task Negative Sampling Enhanced Graph Few-shot Learning

Graph Few-Shot Node Classification (GFSNC) has emerged as a promising approach to address the challenge of learning with limited labeled data in graph-structured networks. Despite the success of Graph Neural Networks (GNNs) in node classification tasks, their performance heavily depends on the availability of abundant labeled data, which is often impractical in real-world scenarios. To tackle this issue, GFSNC adopts the episodic meta-learning paradigm, where models are trained on a series of meta-tasks. However, existing methods face two critical limitations: (i) they focus on local distributions within individual meta-tasks, neglecting the global data distribution, and (ii) they optimize models to minimize intra-class distances without adequately addressing inter-class separability, leading to suboptimal performance. This paper presents TaskNS, a novel GFSNC framework that introduces task-negative samples into meta-training tasks to address these limitations. By incorporating samples from classes outside the current meta-task, our framework enables the model to gradually learn the global distribution of the graph data. Additionally, we design a novel loss function that enhances the model's ability to distinguish between different classes of query samples. This loss function not only ensures high intra-class compactness but also maximizes the inter-class separation by leveraging task-negative samples. To further enhance the quality of task-negative samples, we propose an h-hop-neighbors-based sampling method that leverages the topological structure of a graph. It selects task-negative samples that are structurally close to query samples, ensuring that they are informative and challenging for the model to classify. Extensive experiments on four benchmark datasets demonstrate the effectiveness of TaskNS, achieving average improvements of 4.6% in accuracy (ACC) and 4.9% in F1-score over state-of-the-art methods.