David L Waltz, in Memoriam

tion after completing his dissertation in 1972 at the Massachusetts Institute of Technology Artificial Intelligence Laboratory (MIT AI Lab). That dissertation created the field of constraint propagation by showing that constraints and a rich but simple descriptive system were sufficient to recover threedimensional information from a two-dimensional projection. Besides an education, Dave picked up a passion for the highenergy atmosphere that propelled the MIT AI Lab to prominence — an atmosphere that he spent the rest of his life re-creating. In 1973, Dave Waltz with Richard P. Gabriel in tow headed west from MIT to the University of Illinois at Urbana-Champaign (UIUC) with the goals of starting a first-rate AI program and creating a lab in the image of the MIT AI Lab. All they had were an enthusiastic home in the Coordinated Science Laboratory, some friendly faculty in the Electrical Engineering department, a PDP-10, a shaky connection to the Advanced Research Projects Agency Network (ARPANET), and a small but eager coterie of misfit graduate students. Dave taught AI, and his passion and deep curiosity attracted top-notch visitors and more students; he and Gabriel fleshed out the computational infraArticles