AI Briefing
KO

Can Large Language Models Improve Few-shot Retrieval Performance for Complex Question Answering

·2026.07.16 09:00

Key point

This introduces PromptRank, a technique that uses LLMs to find efficient document paths for complex Multi-hop Question Answering (MQA).

Details

To answer complex questions, Multi-hop Question Answering (MQA) capability—which requires going through multiple stages of reasoning to find scattered information—is essential. Generally, an MQA system consists of a Retriever that finds relevant documents and a Reader that generates the answer.

However, building a high-quality Question-Path dataset for MQA is very costly, and the data scarcity problem is especially severe for low-resource languages or specific domains. Existing data-efficient retrieval methods have mainly been limited to single-hop QA.

To address this, the proposed PromptRank operates in two stages.

  • Stage 1 (Unsupervised Retrieval): A simple unsupervised method such as TF-IDF is used to select an initial set of document paths that are likely to be relevant to the question.
  • Stage 2 (Reranking): An LLM is used to reassess (rerank) the relevance of the selected paths to the question.

The core of PromptRank lies in scoring by calculating the Conditional Likelihood—the probability that a given question would be generated given a specific document path. This makes it possible to achieve sophisticated retrieval performance in complex multi-hop reasoning settings while minimizing data construction costs.

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