STP: Self-play LLM Theorem Provers with Iterative Conjecturing and Proving
Kefan DongTengyu Ma
Presents Self-play Theorem Prover, a dual-agent framework where a language model alternates between generating challenging mathematical conjectures and proving them, doubling previous training success rates on LeanWorkbook and achieving state-of-the-art results on competitive benchmarks like miniF2F.
Formal mathematical reasoning using large language models has become a central benchmark for artificial intelligence. However, standard reinforcement learning and expert iteration methods—which alternate between sampling proofs and retraining on correct ones—consistently plateau because correct proofs for challenging problems are exceedingly rare. As a result, massive amounts of compute are wasted generating incorrect proofs, leaving models unable to self-improve without continuous human-annotated data.
The article introduces the Self-play Theorem Prover, an automated framework designed to overcome this data scarcity by enabling continuous self-improvement. The study evaluates whether a dual-role self-play architecture can generate its own adaptive curriculum of mathematical conjectures and proofs to improve formal proving performance in systems like Lean and Isabelle.
The researchers designed an architecture where a single model simultaneously acts as a conjecturer, proposing new mathematical statements derived from existing seeds, and a prover, attempting to solve both dataset problems and newly generated conjectures. The conjecturer is iteratively trained on generated conjectures that are approachable yet challenging (where the prover succeeds with positive but low probability) and filtered for elegancy and diversity. The prover is trained on verified solutions. The method was evaluated using Lean 4 on the LeanWorkbook, miniF2F, ProofNet, and PutnamBench datasets, as well as an Isabelle-translated suite using the Llemma-7b base model.
The primary finding is that the Self-play Theorem Prover doubles existing performance benchmarks on training datasets, solving 28.5% of LeanWorkbook statements compared to the prior best result of 13.1% achieved by standard expert iteration. Second, the generated conjectures provide dense training signals: at least 47% of generated conjectures yielded successful proofs during training, compared to standard iteration where fewer than 0.01% of proof attempts on unproven dataset statements succeeded. Third, the final model establishes state-of-the-art results for whole-proof generation methods across multiple benchmarks at 3,200 samples per problem, achieving 65.0% on miniF2F-test, 23.9% on ProofNet-test, and solving 8 out of 644 undergraduate-level competition problems in PutnamBench.
These results demonstrate that automated mathematical goal generation can prevent learning saturation and eliminate the need for ever-larger human-labeled formal datasets. By structuring an adaptive difficulty curve internally, organizations can significantly reduce wasted compute during model training while achieving higher performance on complex reasoning tasks.
For future development, the article recommends incorporating tree search algorithms alongside self-play generation to further expand proof-search capabilities. In addition, practitioners should curate cleaner formal datasets; manual auditing of unproven benchmark problems revealed that 13 out of 20 sampled unproven statements were mathematically flawed or unprovable due to translation errors, setting a natural ceiling on benchmark accuracy. Confidence in the core performance gains is high across both Lean and Isabelle environments, though users should account for the fact that benchmark pass rates are constrained by errors in automated statement formalization.
- Paper: DeepSeekMath: Pushing the Limits of Mathematical Reasoning in Open Language Models, Zhihong Shao et al. (2024). DeepSeekMath introduces GRPO, the reinforcement-learning method underlying much of the reasoning-training context for STP’s iterative prover improvement.
- Paper: Math-Shepherd: Verify and Reinforce LLMs Step-by-step without Human Annotations, Peiyi Wang et al. (2024). Math-Shepherd shows how automatically estimated intermediate-step rewards can train reasoning models without human annotations, clarifying STP’s use of verified proof attempts as training signals.
- Paper: Teaching Models to Teach Themselves: Reasoning at the Edge of Learnability, Shobhita Sundaram et al. (2026). SOAR carries STP’s self-generated curriculum idea toward harder tasks by training a teacher to create stepping-stone questions that improve a student model.
- Paper: Learning to Reason with Curriculum I: Provable Benefits of Autocurriculum, Nived Rajaraman et al. (2026). This work generalizes adaptive practice selection into a theoretical autocurriculum framework, extending STP’s empirical strategy of choosing conjectures matched to current prover ability.
