arXiv:2501.09186cs.IRcs.AI2025-01被引 31

用大模型动态引导检索,突破传统召回瓶颈。

Guiding Retrieval using LLM-based Listwise Rankers

  • 设计可支持列表式重排的大模型引导检索算法
  • 在nDCG@10上提升最多13.23%,召回率提高28.02%
  • 适合受限初始结果池的高效检索场景

大语言模型(LLM)在列表式重排任务中表现优异,但传统的检索-重排流程受限于召回边界问题:未被初始检索到的相关文档将永久排除。现有自适应检索方法不适用于列表式重排,因其假设文档得分独立于其他文档。本文提出一种适配列表式重排的自适应检索算法,通过融合初始排序结果与已见相关文档的反馈信息来引导检索过程。在多种LLM重排器、第一阶段检索器及反馈源上的实验表明,该方法在保持总LLM推理次数不变的前提下,可使nDCG@10提升最高达13.23%,召回率提升28.02%,且自适应过程开销极小。该工作为在初始结果池受限(如旧系统或高成本语义检索)场景下应用大模型搜索开辟了新路径。

原文摘要 · Abstract (English)

Large Language Models (LLMs) have shown strong promise as rerankers, especially in ``listwise'' settings where an LLM is prompted to rerank several search results at once. However, this ``cascading'' retrieve-and-rerank approach is limited by the bounded recall problem: relevant documents not retrieved initially are permanently excluded from the final ranking. Adaptive retrieval techniques address this problem, but do not work with listwise rerankers because they assume a document's score is computed independently from other documents. In this paper, we propose an adaptation of an existing adaptive retrieval method that supports the listwise setting and helps guide the retrieval process itself (thereby overcoming the bounded recall problem for LLM rerankers). Specifically, our proposed algorithm merges results both from the initial ranking and feedback documents provided by the most relevant documents seen up to that point. Through extensive experiments across diverse LLM rerankers, first stage retrievers, and feedback sources, we demonstrate that our method can improve nDCG@10 by up to 13.23% and recall by 28.02%--all while keeping the total number of LLM inferences constant and overheads due to the adaptive process minimal. The work opens the door to leveraging LLM-based search in settings where the initial pool of results is limited, e.g., by legacy systems, or by the cost of deploying a semantic first-stage.

大模型检索列表式重排自适应检索召回优化

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