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home / papers / 2026 / Challenging the Boundaries of Reasoning: An Olympiad-Level Math Benchmark for Large Language Models

Challenging the Boundaries of Reasoning: An Olympiad-Level Math Benchmark for Large Language Models

Paper · 2026 · Haoxiang Sun, Yingqian Min, Zhipeng Chen et al.

Summary

Current math benchmarks no longer separate the strongest reasoning LLMs, because top models score close to the ceiling. Existing Olympiad-style sets also tend to be small, English-only, scraped from the web, or reliant on LLM judges. The authors address this with OlymMATH, a bilingual (English/Chinese) collection of 350 Olympiad-level problems. They took the problems by hand from printed magazines and textbooks to reduce contamination, and experts checked them. The benchmark combines two evaluation styles:

  • Answer-checked subsets: two subsets of computational problems with numerical answers, verified automatically with sympy.
  • Formal subset: a set of problems formalized in Lean 4, where a proof only counts if it compiles, so reasoning is checked step by step.

An n-gram leakage test suggests lower contamination than PolyMath. Leading reasoning models perform poorly on the hard subset. Accuracy is consistently lower on Chinese versions than on English ones. Case studies show models sometimes reach correct answers through heuristic guesses instead of valid derivations. This matters because it shows that final-answer accuracy can overstate real reasoning ability.

Key points

  • The subsets are OlymMATH-EASY and OlymMATH-HARD (100 numerical problems each) and OlymMATH-LEAN (150 Lean 4 problems). They cover algebra, geometry, number theory and combinatorics.
  • Accuracy on OlymMATH-HARD (EN) was 19.5% for DeepSeek-R1, 31.2% for o3-mini and 58.4% for Gemini 2.5 Pro Exp.
  • On OlymMATH-LEAN, DeepSeek Prover V2 7B and Goedel Prover V2 8B solved no combinatorics problems. Kimina Prover 8B failed to produce extractable code in 62.0% of responses.
  • The authors have released expert solutions, a visualization tool (OlymMATH-demo), and 582,400 reasoning trajectories collected across 28 models: github.com/RUCAIBox/OlymMATH.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Haoxiang Sun, Yingqian Min, Zhipeng Chen, Xin Zhao and Ji-Rong Wen. 2026. Challenging the Boundaries of Reasoning: An Olympiad-Level Math Benchmark for Large Language Models. Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers).

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.acl-long.792

@inproceedings{sun2026challenging,
  title = {{Challenging the Boundaries of Reasoning: An Olympiad-Level Math Benchmark for Large Language Models}},
  author = {Haoxiang Sun, Yingqian Min, Zhipeng Chen, Xin Zhao and Ji-Rong Wen},
  booktitle = {Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)},
  year = {2026},
  doi = {10.18653/v1/2026.acl-long.792},
  url = {https://doi.org/10.18653/v1/2026.acl-long.792}
}

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