AI agent uses Lean to verify CPython functions, files 418 bug reports
What happened
A formal-methods project on CPython reached the Hacker News front page on November 10. It uses Opus 5.5 to rewrite CPython 3.15.2 functions line by line into Lean, then checks them with tests, formal verification and independent agent review. 4,071 functions have passed, 15.7% of those to be checked, and the project has compiled 418 bug reports. The report covers only part of the codebase; it does not claim CPython is fully formally verified, and does not say whether the bug reports have been confirmed or fixed.
Written by AI from the coverage · updated 2 days ago
Coverage
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- Hacker News front pagePickCPython formalization project uses AI agents to model code in Lean, files 418 bug reports
The CPython formalization project used Opus 5.5 to rewrite CPython 3.15.2 functions line by line in Lean. So far 4,071 functions have passed tests, formal verification and independent agent review, 15.7% of the functions to be checked.
Heat over time
Heat now 3·Comparable peak 9（Nov 10 15:00）·Comparable change over 24 hours -49%
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