His main research interests are in the design, analysis, and implementation of efficient algorithms. Over the past decade these interests revolved around problems induced by practice that arise at the intersection of discrete, numerical, and randomized algorithms. Results involving him include the current best runtime bounds for: solving linear systems corresponding to random walks on undirected/directed graphs, maintaining approximate max-matchings in fully dynamic graphs, reducing the sizes of matrices while preserving L_1-norm structures, and approximating max-flows on undirected graphs.