You road I enter upon and look around! I believe you are not all
that is here;
I believe that much unseen is also here.
—WALT WHITMAN, Song of the Open Road
Many friends, colleagues, and family members read some or all of the manuscript. Among them are Alex Bates, Wilson Bell, Mike Burrows, Walt Chromiak, Michael Isard, Alastair MacCormick, Raewyn MacCormick, Nicoletta Marini-Maio, Frank McSherry, Kristine Mitchell, Ilya Mironov, Wendy Pollack, Judith Potter, Cotten Seiler, Helen Takacs, Kunal Talwar, Tim Wahls, Jonathan Waller, Udi Wieder, and Ollie Williams. Suggestions from these readers resulted in a large number of substantial improvements to the manuscript. The comments of two anonymous reviewers also resulted in significant improvements.
Chris Bishop provided encouragement and advice. Tom Mitchell gave permission to use his pictures and source code in chapter 6.
Vickie Kearn (the book’s editor) and her colleagues at Princeton University Press did a wonderful job of incubating the project and bringing it to fruition.
My colleagues in the Department of Mathematics and Computer Science at Dickinson College were a constant source of support and camaraderie.
Michael Isard and Mike Burrows showed me the joy and beauty of computing. Andrew Blake taught me how to be a better scientist.
My wife Kristine was always there and is here still; much unseen is also here.
To all these people I express my deepest gratitude. The book is dedicated, with love, to Kristine.