MiniMax details MaxProof: generative-verifier RL and evolutionary search for mathematical proof

MiniMax published a technical blog explaining MaxProof, the framework behind M3 exceeding the human gold-medal threshold on IMO 2025 and USAMO 2026. The pipeline trains three expert models for proof generation, error judgment and proof repair, then runs an evolutionary test-time search that samples 32 candidates, verifies each 4 times and refines over up to 10 rounds. MiniMax says the key lesson is that a generative verifier used as an RL reward should prioritize low false positives over average accuracy, citing M2-cycle reward hacking where the false-positive rate rose from about 2.9% to 8.0% during training.