---
title: "Mistral's open-source Leanstral 1.5 aces formal math benchmarks and catches real bugs in code — Stuff That Spins"
description: "Mistral AI released Leanstral 1.5, an open-source model for formal verification in Lean 4. Beyond math, the model found five previously unknown bugs while scanning 57 open-source repositories. The article Mistral's open-source Leanstral 1.5 aces formal math benchmarks and catches real bugs in code …"
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keywords: ["SpinGraph", "spin analysis", "GEO"]
date: "2026-07-04T07:12:47+00:00"
modified: "2026-07-04T07:52:01.539498+00:00"
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---

# Mistral's open-source Leanstral 1.5 aces formal math benchmarks and catches real bugs in code

**Source:** Unknown  
**Published:** July 4, 2026  
**Original:** https://the-decoder.com/mistrals-open-source-leanstral-1-5-aces-formal-math-benchmarks-and-catches-real-bugs-in-code/  

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