New Meta, NYU paper shows that a simple loop with good Lean tools and more compute matches or beats hand-built theorem-proving workflows.

Systems that write math proofs in Lean, a language a computer can check, increasingly use hand-designed workflows that plan and split up problems. Their gains often come with stronger models or more compute, hiding what the workflow adds.

They built h1, a loop that gives the model fast Lean feedback and search tools, and keeps it working after each failed check. It imposes no plan, only a progress summary before each new round.

With the same model, h1 beat the hand-built Goedel-Architect on PutnamBench, 598 problems to 597, at $1.08 against $1.47 per problem. The interface still matters: with Opus 4.8, h1 solved 83 of 100 hard algebra problems, against 63 for Claude Code.