My main research interests are in machine learning theory, approximation algorithms, on-line algorithms, algorithmic game theory / mechanism design, algorithmic fairness, and non-worst-case analysis of algorithms. Many years ago I also did work in AI Planning. I am a member of the Simons Collaboration on the Theory of Algorithmic Fairness.

I am on the Steering Committees for FOCS, ITCS, and FORC, and on the editorial board for JACM. I am also on the Advisory Board of a new open access journal TheoretiCS. I was recently Program Chair for the 2019 Innovations in Theoretical Computer Science (ITCS) Conference, on the Organizing Committee for the STOC 2018 and STOC 2017 Theory Fest, and a member of the SafeToC committee.