Mistral AI Releases Leanstral 1.5 Model for Theorem Proving

Jun 30, 2026

AI Summary

Mistral AI has launched Leanstral 1.5, an advanced formal proof engineering model designed for automated theorem proving and autoformalization. The model features 119 billion parameters, with 6.5 billion active, and offers various capabilities including chat completions and document question answering.

Leanstral 1.5 is an updated model optimized for automated theorem proving and autoformalization.
It includes a total of 119 billion parameters, with 6.5 billion active parameters.
Key features of the model include chat completions, function calling, agents and conversations, and structured outputs.
Additional functionalities encompass OCR, document question answering, embeddings, and audio transcriptions.
The model supports a context length of 256k and is offered at no cost.

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Mistral AI Releases Leanstral 1.5 Model for Theorem Proving

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