arXiv:2507.05633cs.CLcs.AI2025-07ACL被引 8

SARA通过文本与语义向量融合,提升大模型问答的准确性和效率。

SARA: Selective and Adaptive Retrieval-augmented Generation with Context Compression

  • 用文本片段和压缩向量双层表示上下文,兼顾细节与概括。
  • 在9个数据集上平均提升答案相关性17.71、正确性13.72、语义相似度15.53。
  • 适合需要高效利用上下文、追求高准确率的RAG应用。

检索增强生成(RAG)虽扩展了大语言模型的外部知识,但面临有效上下文长度受限和检索文档冗余的问题。纯压缩方法虽减少输入规模,却常丢失影响事实准确性的细粒度信息。我们提出SARA,一个统一的RAG框架,在严格上下文预算下平衡局部精确性与全局知识覆盖。SARA结合自然语言文本片段与语义压缩向量,共同提升上下文效率与答案正确性。其上下文表示分为两个互补层面:1)保留关键实体与数值的细粒度自然语言片段;2)紧凑可解释的向量,用于总结高层语义。一个迭代证据选择模块利用压缩向量动态重排上下文。在9个数据集和5个开源LLM(涵盖Mistral、Llama、Gemma三类模型)上,SARA持续提升答案相关性(+17.71)、正确性(+13.72)和语义相似度(+15.53),证明融合文本与压缩表示对鲁棒、高效的RAG至关重要。

原文摘要 · Abstract (English)

Retrieval-augmented Generation (RAG) extends large language models (LLMs) with external knowledge but faces key challenges: restricted effective context length and redundancy in retrieved documents. Pure compression-based approaches reduce input size but often discard fine-grained details essential for factual accuracy. We propose SARA, a unified RAG framework that balances local precision and global knowledge coverage under tight context budgets. SARA combines natural-language text snippets with semantic compression vectors to jointly enhance context efficiency and answer correctness. It represents contexts at two complementary levels: 1) fine-grained natural-language spans that preserve critical entities and numerical values, and 2) compact, interpretable vectors that summarize high-level semantics. An iterative evidence-selection module employs the compression vectors for dynamic reranking of contexts. Across 9 datasets and 5 open-source LLMs spanning 3 model families (Mistral, Llama, and Gemma), SARA consistently improves answer relevance (+17.71), answer correctness (+13.72), and semantic similarity (+15.53), demonstrating the importance of integrating textual and compressed representations for robust, context-efficient RAG.

RAG上下文压缩大模型知识增强

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