Oct 6, 2026
Lean formalization in OpenAI math repository (Result 102)
Model / AI: OpenAI (unreleased)
machine-checked (formal proof)self-reported (formal proof)
OpenAI's internal frontier model proved and formalized in Lean the main result of 'A Direct Proof of Optimal Max-Cut Hardness'. We prove that approximating Max-Cut on simple unweighted graphs within any fixed factor greater than the Goemans–Williamson constant is NP-hard.
Source read 2026-10-08. Cataloged from OpenAI's formalization.yaml (Family 102). The Lean development was not rebuilt locally.