"A formal proof can be produced by a human, a search procedure, or an LLM, while a trusted checker independently verifies that it follows from the stated axioms and inference rules."
Lean's reference manual explains that its kernel accepts a proof only when the formal theorem follows from declared definitions, axioms, and imported results. The checker can validate the output independently of how the proof was generated. Source year is estimated from the live reference manual consulted in 2026.
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