MathDebugger: A Benchmark for Type-Aware Error Detection in Synthetic Math Data

Hao Liang, Meiyi Qiang, Yuying Li, Zefeng He, Xiaochen Ma, Ruichuan An, Yongzhen Guo, Zhengzhou Zhu, Bin Cui, Wentao Zhang


Abstract
Synthetic math data is widely used to scale LLM training, but its correctness is not guaranteed. We introduce MathDebugger, the first text-only, type-aware benchmark for jointly detecting *and* classifying errors in synthetic mathematical questions and answers. MathDebugger contains 2,000 correct questions, 2,000 erroneous questions (balanced across four fine-grained error types), and 2,000 annotated answers (610 erroneous, across three error types), each annotated with both a correctness label and an error-type label, with per-error-type Fleiss’ 𝜅 ranging from 0.69 to 0.88. On 14 SOTA LLMs (6 closed-source, 8 open-source, 1.5B–72B) and 3 process reward models, even advanced systems such as GPT-o3 and DeepSeek-R1 remain far from saturating the benchmark, particularly on fine-grained error-type detection; we further surface a *solving-vs-verifying* gap that causes math-tuned and long-chain-reasoning models to trail their general-purpose siblings. Error-type annotations also provide actionable supervision for correction, with gains that are significant under paired bootstrap (p<0.01). Code and data: [https://anonymous.4open.science/r/MathDebugger-7C4A/README.md](https://anonymous.4open.science/r/MathDebugger-7C4A/README.md)
Anthology ID:
2026.emnlp-main.608
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:
14001–14018
Language:
URL:
https://aclanthology.org/2026.emnlp-main.608/
DOI:
Bibkey:
Cite (ACL):
Hao Liang, Meiyi Qiang, Yuying Li, Zefeng He, Xiaochen Ma, Ruichuan An, Yongzhen Guo, Zhengzhou Zhu, Bin Cui, and Wentao Zhang. 2026. MathDebugger: A Benchmark for Type-Aware Error Detection in Synthetic Math Data. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 14001–14018, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MathDebugger: A Benchmark for Type-Aware Error Detection in Synthetic Math Data (Liang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.608.pdf