Last week, a 23-year-old with no advanced math training typed an Erdős problem into ChatGPT on a random Monday afternoon and got back what appears to be a genuine solution to a 60-year-old conjecture. Terence Tao — arguably the greatest living mathematician — looked at it, said it was real, and noted that the AI had used a method no human had thought to apply.

That last part is the one I keep turning over.

Something happened last week that I keep turning over in my mind.

GPT-5.4 Pro solved an open problem in mathematics. Not a benchmark problem. Not a competition problem with a known answer sitting in some training set. An actual unsolved research problem in combinatorics: improving the lower bounds on a sequence called H(n), which arises in Ramsey-style hypergraph theory. The solution has been reviewed by the problem contributor, Will Brian, confirmed to be correct, and is being written up for publication. The two researchers who elicited the solution, Kevin Barreto and Liam Price, have the option to be listed as coauthors.