In a post on X, @__eknight__ said GPT-5.6 Sol Ultra produced a proof of the 50-year-old Cycle Double Cover Conjecture using 64 subagents in just under an hour, one day after the model became generally available. The same post says the company is sharing both the prompt and the proof publicly. So far, the only source for the claim is that company-linked X announcement, but it was quickly amplified by people including Tyler Cowen and several math and AI accounts.