When Relevance Is Not Evidence: A Controlled Diagnostic of Claim-Conditioned Support Ranking

Ke Lu


Abstract
Retrieval-augmented generation ranks passages by topical relevance or semantic similarity, but generation needs passages that actually support a target claim. We study when these targets come apart, framing the task as claim-conditioned support ranking over a constructed candidate shortlist: given a query, an explicit target claim, and a small fixed set of candidates, rank them by evidential support. We build a controlled, typed development set of 175 controlled contrastive examples spanning seven spurious-evidence cues, each pairing one supporting passage with one targeted non-support passage expressing the designated cue, plus neutral distractors. We evaluate with a corrected, tie-aware protocol that uses role-free evaluator-facing opaque identifiers and neutral tie handling. Tested query-only relevance rankers (lexical, dense, and a cross-encoder) yield tie-aware focal-pair error rates of roughly 18–34%; in the BM25 cue decomposition, several strata have high error, including negation and relation directionality; a gold-claim NLI reference—which receives information the rankers do not—reduces but does not eliminate the error. We argue that evidence-ranking evaluation should explicitly condition on the claim whose support is assessed, and sketch a typed, claim-conditioned evaluation direction that separates relevance, support, and source attributes. This is a controlled diagnostic on development data: it does not estimate real-world prevalence or provide a deployable method.
Anthology ID:
2026.akbc-1.7
Volume:
Proceedings of the 11th Workshop on Automated Knowledge Base Construction (AKBC 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Jan-Christoph Kalo, Ndapa Nakashole, Simon Razniewski, Fabian M. Suchanek, Andreas Vlachos, Andrew McCallum
Venues:
AKBC | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
88–93
Language:
URL:
https://aclanthology.org/2026.akbc-1.7/
DOI:
Bibkey:
Cite (ACL):
Ke Lu. 2026. When Relevance Is Not Evidence: A Controlled Diagnostic of Claim-Conditioned Support Ranking. In Proceedings of the 11th Workshop on Automated Knowledge Base Construction (AKBC 2026), pages 88–93, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
When Relevance Is Not Evidence: A Controlled Diagnostic of Claim-Conditioned Support Ranking (Lu, AKBC 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.akbc-1.7.pdf