用隐空间向量替代文本查询,让大模型自研检索与生成
Latent Abstraction for Retrieval-Augmented Generation

- 用模型自身隐状态生成检索向量,不依赖自然语言查询
- 在6个问答数据集上超越现有RAG方法,减少检索调用次数
- 自动判断是否够证据,适合追求高效准确的系统集成
检索增强生成(RAG)已成为提升大语言模型外部知识能力、减少幻觉和提高事实性的标准方法。然而,现有系统在每一步都需生成自然语言查询,并严格分离检索器与生成器,限制了大模型的表征潜力。我们提出LAnR(Latent Abstraction for RAG),一种统一框架,使单个大模型在自身隐空间内联合完成编码、检索与生成。LAnR不生成文本查询,而是从指定[ PRED ]标记的隐藏状态生成密集检索向量,并与同一模型编码的文档表示匹配。此外,LAnR通过轻量级MLP控制头基于相同隐藏状态自适应判断是否已获取足够证据,消除了独立检索器和显式的停止推理。该设计基于实证观察:答案词元熵能可靠指示检索充分性。在六个涵盖单跳与多跳设置的QA基准上的实验表明,LAnR优于现有RAG方法,同时通过减少检索调用次数和更紧密的模型集成实现了更高的推理效率。
原文摘要 · Abstract (English)
Retrieval-Augmented Generation (RAG) has become a standard approach for enhancing large language models (LLMs) with external knowledge, mitigating hallucinations, and improving factuality. However, existing systems rely on generating natural language queries at each hop and maintaining a strict architectural separation between retriever and generator, preventing them from leveraging the full representational capacity of the LLM. We propose \textbf{LAnR} (Latent Abstraction for RAG), a unified framework in which a single LLM jointly performs encoding, retrieval, and generation entirely within its own latent space. Rather than generating textual queries, LAnR produces dense retrieval vectors from the hidden states of a designated \texttt{[PRED]} token and uses them to match against encoded document representations from the same model. Furthermore, LAnR adaptively decides when sufficient evidence has been retrieved using a lightweight MLP control head over those same hidden states, eliminating both the separate retriever and explicit token-level stopping reasoning. This design is motivated by our empirical observation that answer token entropy reliably signals retrieval sufficiency. Extensive experiments on six QA benchmarks spanning single-hop and multi-hop settings demonstrate that LAnR outperforms existing RAG methods, while achieving improved inference efficiency through reduced number of retrieval calls and tighter model integration.
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