OpenAI Claims GPT-5.6 Solved 50-Year-Old Math Conjecture, Proof Unverified

OpenAI released a 3-page proof of the Cycle Double Cover Conjecture on July 10, 2026, attributing it entirely to GPT-5.6 Sol Ultra running 64 cooperative agents in parallel. The conjecture, unsolved since the 1970s, posits that every bridgeless graph has a set of cycles covering each edge exactly twice. The proof uses the 8-flow theorem and a linear algebra argument, with its validity hinging on a key claim in Lemma 2.2. No independent mathematician has verified the proof, and it has not been formalized in any proof-checking system like Lean or Coq. Notably, the prompt used to generate the proof instructed the model to assume a solution exists and explicitly forbade it from concluding the problem was still open.