Knowledge-Based Domain-Oriented Data Augmentation for Enhancing Unsupervised Sentence Embedding

Recently, unsupervised sentence embedding models have received significant attention in downstream natural language processing tasks. Using large language models (LLMs) for data augmentation has led to considerable improvements in previous studies. Nevertheless, these strategies emphasize data augmentation with extensive generic corpora, neglecting the consideration of few-shot domain data. The synthesized data lacks fine-grained information and may introduce negative sample noise. This study introduces a novel pipeline-based data augmentation method that leverages LLM to synthesize the domain-specific dataset. It produces both positive and negative samples through entity- and quantity-aware augmentation, utilizing an entity knowledge graph to synthesize samples with fine-grained semantic distinctions, increasing training sample diversity and relevance. We then present a Gaussian-decayed gradient-assisted Contrastive Sentence Embedding (GCSE) model to reduce synthetic data noise and improve model discrimination to reduce negative sample noise. Experimental results demonstrate that our approach achieves state-of-the-art semantic textual similarity performance with fewer synthetic data samples and lesser LLM parameters, demonstrating its efficiency and robustness in varied backbones.