LLMs & Models4 min read
Lean 4
Leanstral 1.5 proves the old rules of AI pricing don't apply to math
Leanstral 1.5, a 6B active-parameter model, saturates miniF2F, solves 587 PutnamBench problems, and uncovers 5 previously unreported bugs in open-source repositories. At roughly $4 per problem, it undercuts Seed-Prover by 75x and Aleph Prover by 15x, challenging the assumption that formal verification requires massive compute budgets.
2026-07-12