OpenAI isn't done cashing in on math's hardest open questions—at least not on the credit for solving them, since the company says it doesn't want the money. Days after claiming a solution to the Navier-Stokes equations, OpenAI told the New York Times it has made "substantial progress" on another Millennium Prize Problem, one of seven grand puzzles the Clay Mathematics Institute has backed with a $1 million bounty since 2000.