Mistral releases Leanstral 1.5 formal verification model

Leanstral 1.5 achieves SOTA on formal verification benchmarks: 87% on FATE-H, 34% on FATE-X, and solves 587/672 PutnamBench problems. It is Apache-2.0 licensed with 6B active parameters and has uncovered 5 previously unknown bugs in open-source repositories. The model is available via HuggingFace and a free API.