SAFE: An LLM-as-Verifier Framework for Evidence-Grounded Multi-Hop Reasoning

Daeyong Kwon, Soyoung Yoon, Seung-Won Hwang


Abstract
Multi-hop QA benchmarks often reward Large Language Models (LLMs) for spurious correctness, where models reach correct answers through invalid intermediate reasoning. We propose SAFE, an LLM-as-verifier framework for evidence-grounded multi-hop QA. Rather than judging only the final answer after generation, SAFE verifies reasoning during generation by checking intermediate steps against the provided passages and previous reasoning trajectory. To make this process checkable, SAFE decomposes reasoning into atomic, evidence-grounded units represented with Knowledge Graph (KG) triples. At train-time, SAFE verifies benchmark supervision under KG-grounded constraints and constructs reliable verifier training data. At inference-time, an external verifier checks each generated step, identifies invalid reasoning, and provides correction feedback before errors propagate. Across three multi-hop QA benchmarks, SAFE improves accuracy by 8.8 pp on average. These results show that evidence-grounded multi-hop QA benefits from shifting LLM-based evaluation from post-hoc answer judgment to stepwise reasoning verification.
Anthology ID:
2026.emnlp-main.853
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:
19755–19788
Language:
URL:
https://aclanthology.org/2026.emnlp-main.853/
DOI:
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Cite (ACL):
Daeyong Kwon, Soyoung Yoon, and Seung-Won Hwang. 2026. SAFE: An LLM-as-Verifier Framework for Evidence-Grounded Multi-Hop Reasoning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 19755–19788, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SAFE: An LLM-as-Verifier Framework for Evidence-Grounded Multi-Hop Reasoning (Kwon et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.853.pdf