Beyond Retrieval: Structuring Evolving and Inconsistent External Knowledge with Proposition Relations for RAG

Noriki Nishida, Fei Cheng, Yuji Matsumoto


Abstract
Real-world knowledge bases evolve over time and accumulate outdated statements, contradictions, and misinformation. LLMs have been reported to be vulnerable to such inconsistent contexts. In this paper, we propose Proposition-Structured RAG (ProStruct-RAG), a framework that continuously structures evolving and inconsistent external knowledge bases using timestamped propositions and inter-proposition relations. ProStruct-RAG represents a document collection as a graph whose nodes are propositions and whose edges capture temporal updates, contradictions, and support relations, retrieves query-relevant knowledge as a relational structure, and uses it for answer generation in RAG. Experiments on multiple open-book temporal QA benchmarks show that ProStruct-RAG outperforms baselines that do not use inter-proposition relations, suggesting that RAG over evolving and inconsistent knowledge benefits from organizing external knowledge before retrieval, rather than relying solely on inference-time reasoning. We release our code and Asteria, a new fictional temporal QA dataset designed to mitigate data contamination.
Anthology ID:
2026.emnlp-main.294
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
6749–6771
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URL:
https://aclanthology.org/2026.emnlp-main.294/
DOI:
Bibkey:
Cite (ACL):
Noriki Nishida, Fei Cheng, and Yuji Matsumoto. 2026. Beyond Retrieval: Structuring Evolving and Inconsistent External Knowledge with Proposition Relations for RAG. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 6749–6771, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Beyond Retrieval: Structuring Evolving and Inconsistent External Knowledge with Proposition Relations for RAG (Nishida et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.294.pdf