Proving Olympiad Inequalities by Synergizing LLMs and Symbolic Reasoning
Paper · 2025 · Zenan Li, Zhaoyu Li, Wen Tang et al.
Summary
The paper tackles automated formal proving of elementary algebraic inequalities from math Olympiads. Pure LLM provers struggle because formal proof data is scarce and the tactic space is huge. Symbolic methods such as cylindrical algebraic decomposition scale poorly and give opaque, non-readable proofs. The authors present LIPS, a neuro-symbolic prover working in Lean.
LIPS is built from an analysis of how humans solve such problems, which it splits into two tactic families:
- Scaling applies a known lemma such as AM-GM or Cauchy-Schwarz. Symbolic tools enumerate these exhaustively, and an SMT solver discards any step that makes the goal false.
- Rewriting produces equivalent transformations. LLMs propose these through format-specific prompts.
The resulting subgoals are pruned with symbolic heuristics based on homogeneity and decoupling. An LLM then ranks the survivors using chain-of-thought.
On 161 competition inequalities, LIPS reaches state-of-the-art results without any extra training data, beating both neural and symbolic baselines in success rate and speed. Its output is a human-readable proof that Lean verifies. This shows that dividing reasoning carefully between LLMs and symbolic engines can make up for limited data.
Key points
- Benchmark: 161 inequalities collected from a trio of sources: the problem collections of Chen (2014) and Tung (2012), along with the AIPS set of Wei et al. (2024).
- Main result: on the 61 Olympiad-sourced problems, LIPS proves 56 within 90 minutes. The previous best method proves 41 and gives no human-readable proofs.
- Tactic split: symbolic scaling uses lemma applications such as
NEQ_AM_GM_...andNEQ_Cauchy_Schwarz_..., plus Muirhead and the tangent-line trick. LLM rewriting uses tactics such asllm_simplify,llm_rearrangeandllm_cancel_denom. - No fine-tuning: unlike INT and AIPS, LIPS needs no synthetic training data. It combines off-the-shelf LLMs with SMT/CAD-style solvers.
- Error detection: the symbolic counterexample search found flaws in community solutions posted on AoPS, for example for the Japan 1997 problem.
Fields, topics and concepts
📚 Shelves 3The field of science this work belongs to (OpenAlex fields).Computer Science · 19,503 worksArtificial Intelligence · 18,805 worksComputational Theory and Mathematics · 496 works
🧭 Topics 2Research subjects and languages the work is about.Language models & pretraining · 4,145 worksReasoning · 1,948 works
Cite
Cite as Zenan Li, Zhaoyu Li, Wen Tang, Xian Zhang, Yuan Yao, Xujie Si, Fan Yang, Kaiyu Yang and Xiaoxing Ma. 2025. Proving Olympiad Inequalities by Synergizing LLMs and Symbolic Reasoning. arXiv:2502.13834.
@misc{li2025proving,
title = {{Proving Olympiad Inequalities by Synergizing LLMs and Symbolic Reasoning}},
author = {Zenan Li, Zhaoyu Li, Wen Tang, Xian Zhang, Yuan Yao, Xujie Si, Fan Yang, Kaiyu Yang and Xiaoxing Ma},
year = {2025},
doi = {10.48550/arxiv.2502.13834},
eprint = {2502.13834},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2502.13834}
}References
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