OpenAI says GPT-5.6 Sol proved a 50-year-old math conjecture in under an hour

OpenAI says its new GPT-5.6 Sol model, running an 'ultra' mode that split work across 64 parallel subagents, produced a proof of the cycle double cover conjecture — an open graph-theory problem since the 1970s — in under an hour, against an eight-hour budget. The three-page proof is public but unverified; mathematicians praised its elegance while flagging missing citations to prior work.