Lean has a new checker: con-leche, a CONsistent LEan CHEcker. This is an external checker for Lean that is proven (in Lean) to be consistent, meaning it does not accept a proof of False.
Joachim Breitner (@nomeata) is the mastermind behind the project.
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I did not expect this. Anthropic just published a Lean proof of Fermat's Last Theorem.
The proof is +13M LoC, more than 5 times the size of Mathlib.
Kevin Buzzard's post:
The proof:
Anthropic's post:
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Here is our postmortem describing new Lean bugs found by OpenAI internal models. They are all fixed in Lean v4.33.1 Many thanks to Daniel Selsam from OpenAI for all the help.
