The Citation Expansion Trap: Operating-Point Control for Fixed-Answer Multi-Hop RAG Citation Repair

Jiawei Li


Abstract
Multi-hop retrieval-augmented generation systems often produce answers with incomplete or noisy citation sets. When the answer text is fixed, citation repair may seem to require only adding retrieved evidence. We show that this view is incomplete: in multi-hop settings, expansion that recovers missing support can also introduce plausible distractors into the evidence bundle. We study fixed-answer citation-set repair as a diagnostic protocol for reporting policies as operating points between support-ID coverage and distractor control. Across a calibrated 5,000-example HotpotQA diagnostic and Qwen2.5-generated outputs on HotpotQA, MuSiQue, and 2Wiki, cross-encoder repair yields cleaner support-ID operating points than BM25 expansion on HotpotQA and 2Wiki, while MuSiQue shifts the policy into a higher-distractor-cost regime under harder compositional transfer. We do not claim universal transfer of absolute performance from HotpotQA alone; the cross-dataset pattern is instead consistent with mechanism-level transfer of the support-distractor operating-point geometry. A single-author audit of 450 unique generated-output cases plus 60 duplicate checks reinforces this caution: support-ID coverage and claim-level citation support can diverge. We therefore recommend an operating-point scorecard for citation repair and separate support-ID diagnostics from stronger claim-level faithfulness claims.
Anthology ID:
2026.groundlm-1.25
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
Venues:
GroundLM | WS
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Publisher:
Association for Computational Linguistics
Note:
Pages:
322–329
Language:
URL:
https://aclanthology.org/2026.groundlm-1.25/
DOI:
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Cite (ACL):
Jiawei Li. 2026. The Citation Expansion Trap: Operating-Point Control for Fixed-Answer Multi-Hop RAG Citation Repair. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 322–329, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
The Citation Expansion Trap: Operating-Point Control for Fixed-Answer Multi-Hop RAG Citation Repair (Li, GroundLM 2026)
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