Mistral AI's open-source formal verification model, Leanstral 1.5.

Mistral AI has released Leanstral 1.5, a large-scale formal verification model optimized for automated theorem proofs in Lean 4. The model employs a 119B parameter MoE architecture, activating only 6.5B parameters per token, and supports ultra-long contexts of up to 256k characters and graphical inputs. It achieves state-of-the-art (SOTA) performance on mathematical proof benchmarks such as miniF2F and PutnamBench. The model is open-source on HuggingFace, supporting both local deployment and online testing.