DANIEL P. RESNICK is Professor of History Emeritus at Carnegie Mellon, and a winner of the Elliot Dunlap Smith Prize for Excellence in Teaching in the College of Humanities and Social Sciences. He is Special Assistant to the President for Academic Affairs. His research interests are post-revolutionary societies, literacy development in Europe and the United States, and the measurement of educational success. He has taught at Harvard University, Sarah Lawrence College, and Stanford University. He joined the Carnegie Mellon faculty in 1966. DANA S. SCOTT is the Hillman University Professor of Computer Science, Philosophy, and Mathematical Logic at Carnegie Mellon. His philosophical interests are the foundations of logic, the philosophy of mathematics, and the semantical analysis of natural language. He has taught at the University of Chicago, the University of California, Berkeley, Stanford University, the University of Amsterdam, Princeton University, Oxford University, and the University of Linz, Austria. He joined the Carnegie Mellon faculty in 1981.