Ryan O'Donnell and Luis von Ahn, both assistant professors of computer science, are recipients of Sloan Research Fellowships for 2009, which include two-year grants of $50,000.

The 14 other computer scientists among the 118 new Sloan Fellows this year include several with Carnegie Mellon ties: Steve Zdancewic of the University of Pennsylvania, who received his undergraduate degree in computer science here, and Tze Sing Eugene Ng of Rice University and Shuchi Chawla of the University of Wisconsin, who both earned their PhDs in computer science here.

"The Sloan Research Fellowships support the work of exceptional young researchers early in their academic careers, and often at pivotal stages in their work," said Paul L. Joskow, president of the Alfred P. Sloan Foundation. "I am proud of the Foundation's rich history in providing the resources and flexibility necessary for young researchers to enhance their scholarship, and I look forward to the future achievement of the 2009 Sloan Research Fellows."

O'Donnell's main research interests are in computational complexity, especially hardness of approximation and computational learning theory. He also has strong interests in discrete harmonic analysis and in probability.

One of Von Ahn's primary research interests is finding techniques for using human processing power to solve problems that computers cannot yet solve, such as understanding images. To that end, he has developed online "games with a purpose," such as the ESP Game, and repurposed a widely used online security tool into a mechanism, called reCAPTCHA, for digitizing old texts.