Quizzing the Translation: A Prover-Grounded Evaluation Metric for NL→FOL

Pu Suo, Ali Emami


Abstract
A standard pipeline for symbolic reasoning over natural-language problems translates them into first-order logic and invokes a theorem prover. The translation step is the bottleneck: swap "every" for "some" and every inference that follows is corrupted. Yet today’s metrics often score more broken translations higher than less broken ones, because BLEU, BERTScore, and Smatch++ reward surface overlap that the worst errors happen to preserve. We introduce SIV, which derives two kinds of probes from the target formula and uses a theorem prover to verify the candidate translation against each. Positive probes are statements the candidate must entail, which detect translations that drop content; contrastive probes are statements the candidate must not entail, which detect translations that assert more than the original. On a controlled pool of perturbed FOLIO translations, the severity of the error accounts for 80% of SIV’s score variance, compared with at most 17% for any prior metric. Across six error classes on a disjoint pool, SIV scores the reference above the perturbed candidate in over 99% of pairs. Because each probe is labeled with what it tests, the failure pattern also supplies a labeled error trace, recovering the perturbation class at macro-F1 0.638, nearly double the score-only baseline. On 434 expert-audited real LLM translations, SIV attains the top AUC, uniquely detects and grades expert-labeled major errors, and abstains, rather than mis-scoring, on out-of-vocabulary translations.
Anthology ID:
2026.emnlp-main.310
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:
7149–7166
Language:
URL:
https://aclanthology.org/2026.emnlp-main.310/
DOI:
Bibkey:
Cite (ACL):
Pu Suo and Ali Emami. 2026. Quizzing the Translation: A Prover-Grounded Evaluation Metric for NL→FOL. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 7149–7166, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Quizzing the Translation: A Prover-Grounded Evaluation Metric for NL→FOL (Suo & Emami, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.310.pdf