Don't let the title fool you: This isn't simply Alan Turing's groundbreaking paper "On Computable Numbers, with an Application to the Entscheidungsproblem" with a handful of footnotes thrown in. While the paper is contained here in its entirety, there is, on average, about a paragraph of explanation for each line of Turing's prose. And before that, there is an extensive introduction to important concepts, starting with the distinctions between rational, irrational, algebraic, transcendental, and computable numbers--all explained in terms that any intelligent undergraduate should be able to understand. No mathematical background is assumed beyond algebra.



The Annotated Turing exceeds even the best undergraduate textbooks in explaining these concepts clearly yet concisely, and in doing so sets up the historical context that Turing worked in. When there is an interesting story to tell about Hilbert or Russell, he tells it. (Russell's life was, after all, sufficiently fascinating to be the subject of a recent comic book, Logicomix.) Those with a more extensive mathematical background will want to skim the early sections, but shouldn't skip them entirely.



What Douglas Hofstadter's Gödel, Escher, Bach did for Gödel's Incompleteness Theorem--a crucial discovery that was poorly understood outside of the domain of professional mathematicians--Petzold's book does for Turing's universal computer. If you have any interest whatsoever in the theory of computing, make this the first book you read.