Bridging the Long-Tail Gap: Robust Retrieval-Augmented Relation Completion via Multi-Stage Paraphrase Infusion

Fahmida Alam, Mihai Surdeanu, Ellen Riloff


Abstract
Large language models (LLMs) struggle with relation completion (RC), both with and without retrieval-augmented generation (RAG), particularly when the required information is rare or sparsely represented. To address this, we propose a novel multi-stage paraphrase-guided relation-completion RAG framework, RC-RAG, that systematically incorporates relation paraphrases across multiple stages. In particular, RC-RAG: (a) integrates paraphrases into retrieval to expand lexical coverage of the relation, (b) uses paraphrases to generate relation-aware summaries, and (c) leverages paraphrases during generation to guide reasoning for relation completion. Experiments with five LLMs on two benchmark datasets show that RC-RAG consistently outperforms several RAG baselines. In long-tail settings, the best-performing LLM augmented with RC-RAG improves by 50.4 Exact Match (EM) points over its standalone performance and surpasses two strong RAG baselines by 30.4 and 16.0 EM points, respectively, without requiring additional model training or fine-tuning.
Anthology ID:
2026.findings-aacl.143
Volume:
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2805–2823
Language:
URL:
https://aclanthology.org/2026.findings-aacl.143/
DOI:
Bibkey:
Cite (ACL):
Fahmida Alam, Mihai Surdeanu, and Ellen Riloff. 2026. Bridging the Long-Tail Gap: Robust Retrieval-Augmented Relation Completion via Multi-Stage Paraphrase Infusion. In Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026, pages 2805–2823, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Bridging the Long-Tail Gap: Robust Retrieval-Augmented Relation Completion via Multi-Stage Paraphrase Infusion (Alam et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-aacl.143.pdf