Benchmarking Testing in Automated Theorem Proving

Jongyoon Kim, Hojae Han, Seung-Won Hwang


Abstract
Recent advances in large language models (LLMs) have shown promise in formal theorem proving, yet evaluating semantic correctness remains challenging. Existing evaluations rely on indirect proxies such as lexical overlap with human-annotated proof,or expensive manual inspection.Inspired by the shift from lexical comparison to test-based evaluation in code generation, we propose T2, a framework that evaluates the semantic correctness of formal theorems: a generated theorem is considered correct only if all dependent successor theorems compile successfully, analogous to integration testing.We construct a benchmark from 5 real-world Lean 4 repositories, comprising 2,206 problems paired with 41 successor theorems on average, automatically extracted without human effort.Experiments demonstrate that while state-of-the-art models achieve high compilation success, they perform significantly worse under our semantic metric.The best model, Claude-Sonnet-4.5, achieves only 38.9% Testing Accuracy on the full set, given both natural language proof and successor theorems as context, revealing a critical gap in current theorem generation capabilities.
Anthology ID:
2026.acl-industry.150
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Yunyao Li, Georg Rehm, Mei Tu
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2241–2260
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-industry.150/
DOI:
Bibkey:
Cite (ACL):
Jongyoon Kim, Hojae Han, and Seung-Won Hwang. 2026. Benchmarking Testing in Automated Theorem Proving. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026), pages 2241–2260, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Benchmarking Testing in Automated Theorem Proving (Kim et al., ACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl/2026.acl-industry.150.pdf