REVIEW 4 major objections 6 minor 2 cited by
Towards Solving More Challenging IMO Problems via Decoupled Reasoning and Proving
T0 review · 4 major / 6 minor · reviewed 2026-08-06 · deepseek-v4-flash
Pith's one-line read A two-model pipeline—one model proposing lemma statements, another verifying them—produces machine-verified Lean proofs for five post-2000 IMO problems.
desk verdict Five Lean proofs and a clean decoupling story, but the missing direct-proving control and unreported attempt pool keep the central claim from being fully established. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing mechanism is the subgoal-lemma bridge. The Reasoner (the authors use Gemini 2.5 Pro) is prompted to think through a proof strategy and output only the formal Lean statements of intermediate theorems, terminated by 'by sorry'; a regular expression extracts the declarations. The Prover (DeepSeek-Prover-v2 7B, CoT variant) then attempts each lemma with up to $k=128$ proof candidates, retaining only lemmas for which at least one attempt succeeds. Finally, a model adept at proof continuation (OpenAI-o3 or Gemini 2.5 Pro) receives the verified lemmas in context and assembles the main proof. The framework also documents a phenomenon the authors call 'contextual blindness': many provers ignore pre-proven standalone lemmas and try to reprove the theorem from scratch, which is why the final stage uses reasoner models rather than the specialized prover.
What would settle it
Publishing the complete list of attempted post-2000 IMO problems with per-problem outcomes, or re-running the pipeline with open-weights models and fully specified prompts, would settle the claim. Concretely: if the attempted set is shown to include many more than the five reported problems, or if an independent run with the same prompts on the stated API models fails to reproduce even one of the five verified proofs, the central claim would be refuted.
Extended reading notes
Core claim
The paper's central claim is that high-level mathematical reasoning and low-level formal proof generation should be performed by distinct, specialized models: a Reasoner that proposes strategic subgoal lemmas as formal statements, and a Prover that verifies them. The authors identify the prevailing training paradigm—reinforcement learning with verifiable rewards, which rewards only final proof success—as the root cause of the reasoning-proving gap, arguing that it degrades the latent reasoning of prover models and encourages brute-force tactic application. As evidence, they report that a specialized prover (Kimina-Prover) scores lower than its general-purpose base model (Qwen2.5-Math-7B-Instruct) on MATH and AIME24, and they present a case study on IMO 2019 P1 in which a monolithic prover's attempts reduce to flat instantiations and tactic calls, while the decoupled Reasoner recovers the shifted-Cauchy structure of the solution. The paper's headline result is that the decoupled framework produces verified Lean proofs for five post-2000 IMO problems that, on the paper's problem set, no prior open-source prover had solved.
Load-bearing premise
The whole result rests on the unstated size of the attempted IMO problem set and on the closed API models used for the final proof assembly: if the five solved problems were selected from a much larger pool, or if the commercial reasoners needed human-tuned prompts or oracle hints, the claim of first success on this problem set loses its force.
Editorial extensions
If this is right
- If the decoupling principle is correct, the poor formal-proving performance of LLMs is not a reasoning deficit but a training and architecture artifact, so the same general-purpose reasoning models that score high on informal benchmarks can be redirected into formal proof search.
- The five verified Lean proofs become concrete baselines: any future open-source prover can be checked against them, and the released verified-lemma dataset gives the community intermediate milestones for problems that remain unsolved.
- The pipeline's bottleneck analysis implies that improving the Prover—either by stronger proof search or by fine-tuning provers to use given lemmas—should directly increase the number of solvable IMO problems, since an oracle experiment with human-proved lemmas solved significantly more.
- The RLVR degradation result suggests that training signals for provers should reward strategic structure or lemma use, not only final proof success, if the community wants provers that scale to olympiad-level problems.
Reading between the lines
- The paper never states how many post-2000 non-geometry IMO problems were attempted, so the five successes cannot yet be converted into a success rate; if the intended denominator is roughly the one hundred non-geometry problems from 2000 to 2024, the correct headline would be 'five of about one hundred,' not simply 'five solved.'
- If the diagnosis generalizes, the same decoupled design should transfer to other proof assistants and to non-competition mathematics: any domain where a strong informal reasoner can name the right intermediate statements while a weaker tactic engine verifies them.
- A testable extension would be to run the full pipeline with an open-weights Reasoner and fully public prompts; if the same five problems still verify, the result would no longer depend on closed API models.
- The Kimina/Qwen degradation comparison is a single model pair, so the claimed RLVR-induced degeneration would be stronger if replicated across other prover/base-model pairs.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes DRP-IMO, a three-stage pipeline for Lean 4 theorem proving in which a general-purpose LLM Reasoner generates formal subgoal lemma statements, an open-source Prover (DeepSeek-Prover-v2, 7B CoT) attempts to verify those lemmas, and a final assembly stage uses OpenAI-o3 or Gemini 2.5 Pro to combine the verified lemmas into a proof of the main IMO problem. The authors report success on five post-2000 non-geometry IMO problems: IMO 2000 P2, IMO 2005 P3, IMO 2011 P3, IMO 2019 P1, and IMO 2020 P2. They also present a qualitative case study on IMO 2019 P1, a small quantitative experiment on reasoning degradation in Kimina-Prover, an oracle experiment suggesting that the Prover is the main bottleneck, and a release of verified lemmas for a broader set of IMO problems. The central claim is that decoupling reasoning from proving enables machine-verified solutions on problems where prior open-source provers have reported no success.
Significance. If the five proofs are correct and the attribution to the decoupled architecture is valid, this is a meaningful advance: it would provide the first open-source-adjacent pipeline that machine-verifies several difficult post-2000 IMO problems, and the released lemma dataset could be a useful resource. The paper also makes a falsifiable architectural claim about the benefit of separating strategic reasoning from tactical proof search. However, the significance is conditional on reproducibility and on controls that the current manuscript does not provide; the final proofs are generated by closed commercial models, and no direct-proving baseline is reported for those models.
major comments (4)
- [Section 3.3 and Appendix B] The final proofs of all five solved problems are produced by OpenAI-o3 or Gemini 2.5 Pro, not by the open-source Prover (DeepSeek-Prover-v2) that is the named Prover component in the paper's framing. The manuscript reports that DeepSeek-Prover-v2 ignores provided lemmas, but it does not report any direct-proving baseline in which OpenAI-o3 or Gemini 2.5 Pro attempt the same five Lean statements without the decoupled subgoal pipeline and with the same compute budget (k=128). Without this ablation, the observed successes cannot be attributed to the decoupled architecture; they may reflect the raw proving capability of the closed models. This is the load-bearing control for the paper's central claim and must be added.
- [Section 4] The evaluation reports only the five successes and never states the total number of non-geometry post-2000 IMO problems that were attempted, nor a per-problem breakdown of lemma-generation and verification outcomes. The abstract's phrase 'solves 5 of these problems' is therefore compatible with a much larger attempted set, and the claim that this problem set is one 'on which no prior open-source prover has reported success' is likewise asserted without a citation or a systematic comparison. The paper should report the full attempted set, the success/failure status of every problem, and the basis for the no-prior-success claim.
- [Sections 3.2, 3.3, and Appendix B] The paper's main evidence consists of five Lean proof scripts, but no build environment, Mathlib version, Lean toolchain version, commit hash, or exact inference prompts and hyperparameters are provided. Several proof scripts use very heavy tactic combinations (e.g., `maxHeartbeats 0`, repeated `nlinarith`, `ring_nf`, `aesop`, `omega`) and contain notation that is not obviously standard Lean 4; as a referee I cannot determine from the text alone whether the Appendix B files compile as printed. The authors should ship a reproducible artifact with exact versions and commands, and confirm that each listed proof compiles in that environment.
- [Section 4.1 and Section 4.2] The qualitative comparison in Section 4.1 is based on three sampled, partially quoted attempts from DeepSeek-Prover-v2 and is not a controlled experiment; it cannot support the claim that the decoupled framework's reasoning path is the cause of success. Similarly, the RLVR-degradation experiment in Section 4.2 uses one base model and one prover derived from it, with no error bars or repetition across models; the reported drops, especially at pass@1, are suggestive but not strong enough to carry the paper's motivational thesis. These sections should be reframed as illustrative or supplemented with a systematic comparison on the solved problem set.
minor comments (6)
- [Section 4] There are typographical errors such as 'experiemnts' in Section 4; the paper should be copy-edited.
- [Section 3.3] The text describing the final proof construction appears twice with slightly different wording; one of the duplicated paragraphs should be removed.
- [Figure 1] Figure 1 is difficult to read at the resolution provided; the subgoal statements and the correspondence between reasoning steps and formal lemmas should be presented more legibly.
- [Table 1] Table 1 reports pass@k only for AIME24 and only pass@1 for MATH; the sampling setup, the number of samples, and whether pass@k is unbiased are not specified, so the numerical comparisons should be interpreted cautiously.
- [Abstract and Section 1] The paper refers to PutnamBench and to the claim that informal accuracy exceeds 80% while formal success is below 8%, but the precise source of these numbers should be cited directly rather than cited only through a general reference.
- [Appendix B] The theorem names are inconsistent across the appendix (e.g., `imo2019_p1` in some places and `imo2020_q2` in others); uniform naming would improve readability.
Circularity Check
No significant circularity: the five claimed IMO solutions are checked by Lean's kernel, the subgoal lemmas are proved before final assembly, and no fitted parameter is renamed as a prediction.
full rationale
After walking the derivation chain, I find no step in which a predicted quantity is definitionally equal to an input, a fitted parameter is renamed as a prediction, or a load-bearing premise is imported solely from the authors' own prior work. The five claimed successes are grounded in Lean code checked against an external kernel; the intermediate lemmas in Appendix B are stated as separate theorems and proved before final assembly. The final proofs (e.g., B.2 for IMO 2019 P1) invoke only the previously proved subgoal lemmas and basic tactics, so the final theorem is not the same object as any single subgoal by construction. The motivating claim that RLVR degrades reasoning (Section 4.2, Table 1) is an empirical comparison between a base model and a fine-tuned prover; it is used to justify the architecture, but the architecture's successes are not defined in terms of that comparison, so the motivation is not circular. The paper's self-citations (HunyuanProver, MPS-Prover) appear only in related work and are not load-bearing. The main weaknesses—the unreported denominator of attempted problems, closed API models performing final assembly, and the absence of a direct-proving baseline for those models—are attribution and reproducibility concerns, not circularity. No specific reduction of a result to its inputs can be quoted; therefore the circularity score is 0.
Assumptions & free parameters
free parameters (1)
- number of proof candidates k =
128
assumptions (2)
- domain assumption Lean 4 kernel and Mathlib are sound and the appended proofs compile
- domain assumption The arithmetic tactics used (nlinarith, omega, ring_nf) solve the stated goals exactly
Cite this review
Pith. "Pith review of Towards Solving More Challenging IMO Problems via Decoupled Reasoning and Proving." pith.science (2026). https://pith.science/paper/PZBEA2OB
@misc{pith2026250706804,
author = {Pith},
title = {Pith review of: Towards Solving More Challenging IMO Problems via Decoupled Reasoning and Proving},
year = {2026},
howpublished = {\url{https://pith.science/paper/PZBEA2OB}},
note = {Machine review of arXiv:2507.06804}
}
read the original abstract
Automated Theorem Proving (ATP) in formal languages is a foundational challenge for AI. While Large Language Models (LLMs) have driven remarkable progress, a significant gap remains between their powerful informal reasoning capabilities and their weak formal proving performance. Recent studies show that the informal accuracy exceeds 80% while formal success remains below 8% on benchmarks like PutnamBench. We argue this gap persists because current state-of-the-art provers, by tightly coupling reasoning and proving, are trained with paradigms that inadvertently punish deep reasoning in favor of shallow, tactic-based strategies. To bridge this fundamental gap, we propose a novel framework that decouples high-level reasoning from low-level proof generation. Our approach utilizes two distinct, specialized models: a powerful, general-purpose Reasoner to generate diverse, strategic subgoal lemmas, and an efficient Prover to rigorously verify them. This modular design liberates the model's full reasoning potential and bypasses the pitfalls of end-to-end training. We evaluate our method on a challenging set of post-2000 IMO problems, a problem set on which no prior open-source prover has reported success. Our decoupled framework successfully solves 5 of these problems, demonstrating a significant step towards automated reasoning on exceptionally difficult mathematical challenges. To foster future research, we release our full dataset of generated and verified lemmas for a wide range of IMO problems, available at https://tencent-imo.github.io/ .
Figures
Forward citations
Cited by 2 Pith papers
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From Solvers to Research: Large Language Model-Driven Formal Mathematics at the Research Frontier
LLM formal provers must shift from competition solvers to research agents that handle open-ended, under-specified frontier mathematics under machine-checked rigor.
-
Re:Form -- Reducing Human Annotations in Scalable Formal Software Verification with RL in LLMs: A Preliminary Study on Dafny
A minimal-prior pipeline with automated data curation and verifier-driven RL lets small LLMs generate verifiable Dafny specifications and beat larger proprietary models on a synthetic compositional benchmark.
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Reviewed August 6, 2026 · model on record in the stance chip above.
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