Medical Bilingualism: Cross-Ontology Graph Retrieval for Incommensurable Knowledge Bases

Zixuan Wang, Ke Lu, Zihan Wang, Junwei Lei, Junhao Dong, Jinyu Guo, Chaomeng Chen


Abstract
Graph-based Retrieval-Augmented Generation (GraphRAG) can fail in interdisciplinary medicine where evidence comes from incommensurable knowledge systems, e.g., Traditional Chinese Medicine (TCM) and Western Medicine (WM). Similarity-driven retrieval in a shared latent space may over-unify heterogeneous concepts, causing semantic collapse (spurious alignments, provenance-blind mixing, and broken multi-hop chains). We propose Xonto-RAG, a cross-ontology GraphRAG framework that avoids ontological unification by constructing a dual-ontology graph with typed bridges induced via LLM-assisted verify-and-vote. A query-aware Relational Graph Attention Network (RGAT) then assembles compact, provenance-tracked multi-hop evidence subgraphs for grounded generation. Across TCM–WM benchmarks, Xonto-RAG outperforms strong RAG/GraphRAG baselines, seeing up to +22.2% accuracy on MLEC-QA TCWM (vs. OG-RAG), 77.0% accuracy with a 7B backbone, and 85.1% faithfulness on MLEC-TCM, while reducing semantic-collapse failures and yielding interpretable reasoning chains.
Anthology ID:
2026.emnlp-main.201
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:
4591–4612
Language:
URL:
https://aclanthology.org/2026.emnlp-main.201/
DOI:
Bibkey:
Cite (ACL):
Zixuan Wang, Ke Lu, Zihan Wang, Junwei Lei, Junhao Dong, Jinyu Guo, and Chaomeng Chen. 2026. Medical Bilingualism: Cross-Ontology Graph Retrieval for Incommensurable Knowledge Bases. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 4591–4612, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Medical Bilingualism: Cross-Ontology Graph Retrieval for Incommensurable Knowledge Bases (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.201.pdf