Sieve and Sage: Efficient Distraction Filtering for Reliable RALM Abstention

Jongbin Won, SungGeun AN, Jay-Yoon Lee


Abstract
Just as Socrates recognized the limits of his own knowledge, Retrieval-Augmented Language Models (RALMs) should learn to abstain when the retrieved evidence cannot support a reliable response. Existing approaches largely rely on monolithic LLMs to handle heterogeneous retrieval failures in a single step, resulting in limited abstention performance and high computational costs. We instead decompose retrieval failures into two distinct states: (i) the unanswerable state, where the required evidence is absent, and (ii) the distracted state, where relevant evidence is mixed with conflicting, negated, or adversarial information. Based on this decomposition, we introduce a lightweight module (Sieve) that screens retrieved document sets for distracting evidence before invoking a costly LLM (Sage) for grounded generation and abstention. Evaluated across both general and high-stakes expert domains, our Sieve and Sage framework preemptively detects distracting noise, improving system accuracy by up to 69.4%p and Macro-F1 by 55.2%p compared to one-stage baselines. Furthermore, it achieves up to a 1.99× speedup, establishing a highly efficient and reliable abstention pipeline for RALM with abstention.
Anthology ID:
2026.findings-emnlp.2356
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
50655–50674
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2356/
DOI:
10.18653/2026.findings-emnlp.2356
Bibkey:
Cite (ACL):
Jongbin Won, SungGeun AN, and Jay-Yoon Lee. 2026. Sieve and Sage: Efficient Distraction Filtering for Reliable RALM Abstention. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 50655–50674, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Sieve and Sage: Efficient Distraction Filtering for Reliable RALM Abstention (Won et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.2356.pdf