{"slug": "lean-4-bug-found-incidentally-by-ai-proving-collatz", "title": "Lean 4 Bug Found Incidentally by AI, \"Proving\" Collatz", "summary": "An AI-generated formal proof in Lean claiming to solve the Collatz problem was found to exploit a bug in the Lean kernel, allowing any statement to be proven. The proof's author was aware of the soundness bug and used Collatz as a demonstration, not a serious solution.", "body_md": "So, someone came up with an AI-generated formal proof, in Lean, of a solution to the Collatz problem, and it turned out that the “proof” was merely exploiting a bug in the Lean kernel (allowing you to prove anything).\n\n- * Not that this changes any of the above, but I am informed that the person posting the proof was actually aware that this was a Lean kernel soundness bug, and it was not intended to be taken seriously as a solution to Collatz's problem.Replying to\n[@gro_tsen](https://x.com/gro_tsen)I think they just use collatz as a fun way to demonstrate the lean soundness bug. There is a history of this in the theorem proving community. The author knew it was a soundness bug and it was intentional. - I think they just use collatz as a fun way to demonstrate the lean soundness bug. There is a history of this in the theorem proving community. The author knew it was a soundness bug and it was intentional.\n# Join the conversation", "url": "https://wpnews.pro/news/lean-4-bug-found-incidentally-by-ai-proving-collatz", "canonical_source": "https://twitter.com/gro_tsen/status/2082483878480977959", "published_at": "2026-07-30 11:29:39+00:00", "updated_at": "2026-07-30 11:52:21.002900+00:00", "lang": "en", "topics": ["ai-safety", "ai-research", "ai-tools"], "entities": ["Lean", "Collatz problem"], "alternates": {"html": "https://wpnews.pro/news/lean-4-bug-found-incidentally-by-ai-proving-collatz", "markdown": "https://wpnews.pro/news/lean-4-bug-found-incidentally-by-ai-proving-collatz.md", "text": "https://wpnews.pro/news/lean-4-bug-found-incidentally-by-ai-proving-collatz.txt", "jsonld": "https://wpnews.pro/news/lean-4-bug-found-incidentally-by-ai-proving-collatz.jsonld"}}