Harry Lewis is Gordon McKay Professor of Computer Science at Harvard University, where he has taught computer science since 1974. Both Bill Gates and Mark Zuckerberg have been among his many students. He holds the AB and PhD degrees in Applied Mathematics from Harvard, and has served both as Dean of Harvard College and as interim Dean of Harvard’s John A. Paulson School of Engineering and Applied Sciences. Professor Lewis serves as a Technical Advisor to Zerho. He is also the author of many books, including the forthcoming Essential Discrete Mathematics for Computer Scientists (with Rachel Zax).