I study mathematics, specializing in Algebra, Combinatorics and Number Theory. I am the Thomas Jefferson Professor of Mathematics at the University of Virginia, the Vice President of the American Mathematical Society, and the Chair of the Mathematics Section of the American Association for the Advancement of Science. I am an Honorary Professor at the Indian Institute of Technology (Guwahati). I am actively involved in mentoring young mathematicians of all ages.

I spend much of my spare time outdoors and with my family. I enjoy surfing, SCUBA diving, cycling, running, and swimming. I was formerly a member of the Timex-Trek Factory Triathlon Team (2014-2018), and I have represented Team USA in the 2012, 2013, and 2014 ITU World Cross Triathlon Championship. In the 1980s I raced bicycles.