Checked fact 179218 Oct 2026Research

The Lean home page describes Lean as an open-source programming language and proof assistant that enables correct, maintainable and formally verified code, and says Lean lets you write precise, verifiable code and formal proofs.

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Lean is an open-source programming language and proof assistant that enables correct, maintainable, and formally verified code ... Lean lets you write precise, verifiable code and formal proofs.

What the source said when we opened it, on 18 Oct 2026.

The source

Lean: programming language and proof assistant
Lean FRO / Lean project

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Checked

Checked by the notis newsroom on 18 Oct 2026, against the source above.

In the story

How Lean checks an AI-written proof, and where that stops 18 Oct 2026

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“The Lean home page describes Lean as an open-source programming language and proof assistant that enables correct, maintainable and formally verified code, and says Lean lets you write precise, verifiable code and formal proofs.” ai notis, checked 18 Oct 2026. Source: Lean: programming language and proof assistant (Lean FRO / Lean project). https://ainotis.com/c/1792

As a reference (APA style)

ai notis. (2026, October 18). The Lean home page describes Lean as an open-source programming language and proof assistant that enables correct, maintainable and formally verified code, and says Lean lets you write precise, verifiable code and formal proofs [Checked claim 1792]. ai notis. https://ainotis.com/c/1792

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