# Leanstral 1.5: Proof Abundance for All

DevFeed: [Leanstral 1.5: Proof Abundance for All](<https://devfeed.tech/articles/leanstral-1-5-proof-abundance-for-all-7022.md>)

Original publisher: [Read original article](<https://mistral.ai/news/leanstral-1-5/>)

Published: 2026-07-02T13:55:54Z

Content type: release

Language: en

Sources: [Mistral AI Blog](<https://devfeed.tech/sources/mistral-ai-blog.md>)

Topics: [Lean](<https://devfeed.tech/topics/lean.md>), [Formal methods](<https://devfeed.tech/topics/formal-methods.md>), [Artificial Intelligence](<https://devfeed.tech/topics/ai.md>), [Open Source](<https://devfeed.tech/topics/open-source.md>), [hugging face](<https://devfeed.tech/topics/hugging-face.md>), [API](<https://devfeed.tech/topics/api.md>), [Code](<https://devfeed.tech/topics/code.md>)

Tags: [apache](<https://devfeed.tech/tags/apache.md>), [api](<https://devfeed.tech/tags/api.md>), [code](<https://devfeed.tech/tags/code.md>), [developer](<https://devfeed.tech/tags/developer.md>), [formal-methods](<https://devfeed.tech/tags/formal-methods.md>), [formal-verification](<https://devfeed.tech/tags/formal-verification.md>), [hugging-face](<https://devfeed.tech/tags/hugging-face.md>), [launch](<https://devfeed.tech/tags/launch.md>), [models](<https://devfeed.tech/tags/models.md>), [open-source](<https://devfeed.tech/tags/open-source.md>), [reinforcement-learning](<https://devfeed.tech/tags/reinforcement-learning.md>), [training](<https://devfeed.tech/tags/training.md>)

## AI overview

Mistral releases Leanstral 1.5, an Apache-2.0 licensed model for formal verification in Lean 4. The 6B-active-parameter model reports strong miniF2F, PutnamBench, FATE-H, and FATE-X results, and identifies previously unknown bugs in open-source repositories.

## Source excerpt

The most powerful AI platform for enterprises. Customize, fine-tune, and deploy AI assistants, autonomous agents, and multimodal AI with open models.