Stephen is Executive Director of Information Visualization Research. He works on systems and algorithms for visualizing and interactively exploring large, complex structures; and the general problem of applying computational geometry to visualization of abstract information with the goal of approaching the quality of hand-made graphics. Stephen is one of the authors of the Graphviz system. His group also created the core software for Vizgems, a software platform run by AT&T for its internal operations and enterprise customers. Vizgems collects, analyzes and displays near-realtime information at large scale for numerous managed services, and currently has about 100,000 endpoint devices. Stephen received a Ph.D. in Computer Science from Princeton University in 1986.