Proof or Bluff? Evaluating LLMs on 2025 USA Math Olympiad
Paper · 2025 · Ivo Petrov, Jasper Dekoninck, Lyuben Baltadzhiev et al.
Summary
Benchmarks such as MathArena show reasoning LLMs performing at near-elite levels on answer-based contests like AIME and HMMT. However, these tests only check a final number, not whether the argument is valid. The authors test whether current models can write rigorous natural-language proofs. They used the six problems of USAMO 2025, which were uncontaminated because evaluation began within hours of the contest's release. Eight reasoning models each attempted every problem four times. Four experienced olympiad graders scored the anonymized LaTeX solutions on the standard 7-point scale, with two graders per problem and rubrics built from verified AoPS solutions. Results were poor. Gemini-2.5-Pro averaged about 24%, and every other model stayed under 5%. Every model presented its answers as complete solutions, even when they were wrong. The study also classifies errors and documents training-induced quirks. These findings mean that LLM-generated mathematics still requires careful human verification, and that answer-only benchmarks overstate models' reasoning ability.
Key points
- Models tested: Gemini-2.5-Pro, R1, Grok 3, Flash-Thinking, Claude 3.7, QwQ, o1-pro, o3-mini.
- Average totals out of 42 points:
- Gemini-2.5-Pro: 10.1 (about 24.4%), with 6 of its 24 attempts scoring 6/7 or higher.
- R1 and Grok 3: 2.0 each.
- o3-mini: 0.9.
- o1-pro: 1.2, at a cost of about $203.
- Across roughly 175 solutions from the models other than Gemini, the only full 7/7 score was a single Grok 3 attempt on Problem 1.
- Graders labeled the first error in each solution as logic, assumption, creativity, or algebra/arithmetic. Flawed logic was the most common category. Models also often dismissed key steps as "trivial," which was especially frequent for o3-mini.
- Observed artifacts include:
- placing answers in boxes when no single answer was appropriate (QwQ reduced "all even k" to 2);
- generalizing from a single example;
- Gemini inventing citations to papers that do not exist.
- An attempt to grade solutions automatically with an LLM judge, given the rubric and reference solution, was unsuccessful.
Fields, topics and concepts
📚 Shelves 5The field of science this work belongs to (OpenAlex fields).Computer Science · 19,503 worksArtificial Intelligence · 18,805 worksArts and Humanities · 17,959 worksLanguage and Linguistics · 17,789 worksComputational Theory and Mathematics · 496 works
🧭 Topics 3Research subjects and languages the work is about.Language models & pretraining · 4,145 worksReasoning · 1,948 worksEvaluation & benchmarks · 1,394 works
Cite
Cite as Ivo Petrov, Jasper Dekoninck, Lyuben Baltadzhiev, Maria Drencheva, Kristian Minchev, Mislav Balunović, Nikola Jovanović and Martin Vechev. 2025. Proof or Bluff? Evaluating LLMs on 2025 USA Math Olympiad. arXiv:2503.21934.
@misc{petrov2025proof,
title = {{Proof or Bluff? Evaluating LLMs on 2025 USA Math Olympiad}},
author = {Ivo Petrov, Jasper Dekoninck, Lyuben Baltadzhiev, Maria Drencheva, Kristian Minchev, Mislav Balunović, Nikola Jovanović and Martin Vechev},
year = {2025},
doi = {10.48550/arxiv.2503.21934},
eprint = {2503.21934},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2503.21934}
}References
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