Millennium Prize Problems
Because Perelman published his papers over the Internet rather than in a peer-reviewed journal, as required by the Clay Math Institute's rules, he was not initially offered CMI’s award, though representatives for the organization indicated they might relax their requirements in his case. Complicating their decision was uncertainty over whether Perelman would accept the money; he publicly stated that he would not decide until the award was offered to him. Finally, in 2010, CMI offered Perelman the reward for proving the Poincaré conjecture, and Perelman refused.