leanstral

Introducing Leanstral 1.5, a 119B parameter (6B active) open model for formal proof engineering in Lean 4, achieving 100% on miniF2F, state-of-the-art scores on PutnamBench and FATE benchmarks, and discovering previously unknown bugs in open-source repositories.

Today, we are releasing Le Chaton L∃∀N, aka Leanstral 1.5, which achieves SOTA performance on graduate algebra benchmarks FATE-H and FATE-X and improves the Pareto Frontier on PutnamBench, solving 587/672 problems with a x10 cheaper budget.