BubbleRAG: Evidence-Driven Retrieval-Augmented Generation for Black-Box Knowledge Graphs

Fuente: arXiv
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Main Authors: Pan, Duyi, Lou, Tianao, Li, Xin, Song, Haoze, Wu, Yiwen, Deng, Mengyi, Yang, Mingyu, Wang, Wei
Format: Preprint
Published: 2026
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author Pan, Duyi
Lou, Tianao
Li, Xin
Song, Haoze
Wu, Yiwen
Deng, Mengyi
Yang, Mingyu
Wang, Wei
author_facet Pan, Duyi
Lou, Tianao
Li, Xin
Song, Haoze
Wu, Yiwen
Deng, Mengyi
Yang, Mingyu
Wang, Wei
contents Large Language Models (LLMs) exhibit hallucinations in knowledge-intensive tasks. Graph-based retrieval augmented generation (RAG) has emerged as a promising solution, yet existing approaches suffer from fundamental recall and precision limitations when operating over black-box knowledge graphs -- graphs whose schema and structure are unknown in advance. We identify three core challenges that cause recall loss (semantic instantiation uncertainty and structural path uncertainty) and precision loss (evidential comparison uncertainty). To address these challenges, we formalize the retrieval task as the Optimal Informative Subgraph Retrieval (OISR) problem -- a variant of Group Steiner Tree -- and prove it to be NP-hard and APX-hard. We propose BubbleRAG, a training-free pipeline that systematically optimizes for both recall and precision through semantic anchor grouping, heuristic bubble expansion to discover candidate evidence graphs (CEGs), composite ranking, and reasoning-aware expansion. Experiments on multi-hop QA benchmarks demonstrate that BubbleRAG achieves state-of-the-art results, outperforming strong baselines in both F1 and accuracy while remaining plug-and-play.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20309
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle BubbleRAG: Evidence-Driven Retrieval-Augmented Generation for Black-Box Knowledge Graphs
Pan, Duyi
Lou, Tianao
Li, Xin
Song, Haoze
Wu, Yiwen
Deng, Mengyi
Yang, Mingyu
Wang, Wei
Information Retrieval
Databases
Large Language Models (LLMs) exhibit hallucinations in knowledge-intensive tasks. Graph-based retrieval augmented generation (RAG) has emerged as a promising solution, yet existing approaches suffer from fundamental recall and precision limitations when operating over black-box knowledge graphs -- graphs whose schema and structure are unknown in advance. We identify three core challenges that cause recall loss (semantic instantiation uncertainty and structural path uncertainty) and precision loss (evidential comparison uncertainty). To address these challenges, we formalize the retrieval task as the Optimal Informative Subgraph Retrieval (OISR) problem -- a variant of Group Steiner Tree -- and prove it to be NP-hard and APX-hard. We propose BubbleRAG, a training-free pipeline that systematically optimizes for both recall and precision through semantic anchor grouping, heuristic bubble expansion to discover candidate evidence graphs (CEGs), composite ranking, and reasoning-aware expansion. Experiments on multi-hop QA benchmarks demonstrate that BubbleRAG achieves state-of-the-art results, outperforming strong baselines in both F1 and accuracy while remaining plug-and-play.
title BubbleRAG: Evidence-Driven Retrieval-Augmented Generation for Black-Box Knowledge Graphs
topic Information Retrieval
Databases
url https://arxiv.org/abs/2603.20309