OpenAI's GPT-5.6 Sol Ultra used 64 subagents to prove the Cycle Double Cover Conjecture in under an hour, a problem unsolved for 50 years.

OpenAI has released GPT-5.6 Sol, alongside the cheaper Terra and Luna, ending a two-week preview the Commerce Department kept boxed in.

OpenAI's GPT-5.6 Sol Ultra used 64 subagents to prove the Cycle Double Cover Conjecture in under an hour, a problem unsolved for 50 years.