Cross-Granularity Hypergraph Retrieval-Augmented Generation for Multi-hop Question Answering

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Main Authors: Wang, Changjian, Deng, Weihong, Guan, Weili, Lu, Quan, Jiang, Ning
Format: Preprint
Published: 2025
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author Wang, Changjian
Deng, Weihong
Guan, Weili
Lu, Quan
Jiang, Ning
author_facet Wang, Changjian
Deng, Weihong
Guan, Weili
Lu, Quan
Jiang, Ning
contents Multi-hop question answering (MHQA) requires integrating knowledge scattered across multiple passages to derive the correct answer. Traditional retrieval-augmented generation (RAG) methods primarily focus on coarse-grained textual semantic similarity and ignore structural associations among dispersed knowledge, which limits their effectiveness in MHQA tasks. GraphRAG methods address this by leveraging knowledge graphs (KGs) to capture structural associations, but they tend to overly rely on structural information and fine-grained word- or phrase-level retrieval, resulting in an underutilization of textual semantics. In this paper, we propose a novel RAG approach called HGRAG for MHQA that achieves cross-granularity integration of structural and semantic information via hypergraphs. Structurally, we construct an entity hypergraph where fine-grained entities serve as nodes and coarse-grained passages as hyperedges, and establish knowledge association through shared entities. Semantically, we design a hypergraph retrieval method that integrates fine-grained entity similarity and coarse-grained passage similarity via hypergraph diffusion. Finally, we employ a retrieval enhancement module, which further refines the retrieved results both semantically and structurally, to obtain the most relevant passages as context for answer generation with the LLM. Experimental results on benchmark datasets demonstrate that our approach outperforms state-of-the-art methods in QA performance, and achieves a 6$\times$ speedup in retrieval efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2508_11247
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Cross-Granularity Hypergraph Retrieval-Augmented Generation for Multi-hop Question Answering
Wang, Changjian
Deng, Weihong
Guan, Weili
Lu, Quan
Jiang, Ning
Computation and Language
Artificial Intelligence
Multi-hop question answering (MHQA) requires integrating knowledge scattered across multiple passages to derive the correct answer. Traditional retrieval-augmented generation (RAG) methods primarily focus on coarse-grained textual semantic similarity and ignore structural associations among dispersed knowledge, which limits their effectiveness in MHQA tasks. GraphRAG methods address this by leveraging knowledge graphs (KGs) to capture structural associations, but they tend to overly rely on structural information and fine-grained word- or phrase-level retrieval, resulting in an underutilization of textual semantics. In this paper, we propose a novel RAG approach called HGRAG for MHQA that achieves cross-granularity integration of structural and semantic information via hypergraphs. Structurally, we construct an entity hypergraph where fine-grained entities serve as nodes and coarse-grained passages as hyperedges, and establish knowledge association through shared entities. Semantically, we design a hypergraph retrieval method that integrates fine-grained entity similarity and coarse-grained passage similarity via hypergraph diffusion. Finally, we employ a retrieval enhancement module, which further refines the retrieved results both semantically and structurally, to obtain the most relevant passages as context for answer generation with the LLM. Experimental results on benchmark datasets demonstrate that our approach outperforms state-of-the-art methods in QA performance, and achieves a 6$\times$ speedup in retrieval efficiency.
title Cross-Granularity Hypergraph Retrieval-Augmented Generation for Multi-hop Question Answering
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2508.11247