GPT-5.6 closes 30-year gap in convex optimization, verified in Lean
Original: GPT-5.6 used a prompt to close a 30-year gap in convex optimization
Why This Matters
AI-assisted formal proof verification is accelerating resolution of decades-old open mathematical problems.
On July 15, 2026, a Reddit post on r/math reported that GPT-5.6 used a prompt similar to OpenAI's CDC proof announcement to close a 30-year open problem in convex optimization. The result was formally verified using the Lean proof assistant, earning 726 upvotes at 95% approval.
A post submitted to r/math on July 15, 2026 claimed that GPT-5.6, following a prompting approach analogous to OpenAI's recently announced CDC proof, was used to resolve a long-standing open problem in convex optimization that had remained unsolved for approximately 30 years. The proof generated by the model was subsequently verified using Lean, a formal proof assistant, lending it mathematical rigor beyond informal claim. The post received 726 upvotes with a 95% approval rate, indicating significant engagement from the mathematics community. The submission references OpenAI's earlier CDC proof announcement as a methodological precursor, suggesting that structured prompting techniques are emerging as a reproducible workflow for AI-assisted theorem proving. No additional technical details about the specific problem or the prompting method were available from the post content alone.