American Scientist

Turing (A Novel about Computation).
Christos H. Papadimitriou.
viii + 284 pp. MIT Press, 2003. $24.95.

Christos Papadimitriou's Turing (A Novel about Computation) is an epistolary novel—or rather, an
e-pistolary novel, constructed in large part from "transcripts” of electronic messages exchanged by various characters, some of them human beings and some computers.

The plot structure is familiar: Boy meets girl, boy loses girl, boy gets girl. But that structure is perhaps the least important part of the book, as it ignores the fact that the crucial character in this novel is a computer program. This interactive tutoring program, Turing (in the book, the name is always rendered in a different typeface from the rest of the text), is a simulation of Alan Mathison Turing himself, the founder of the field of computer science and a seminal contributor to essentially all of its major subfields. The simulation is perfectly fluent; the program even writes in Britishisms: maths, programme, telly, labour.

Ethel, a high-flying software guru vacationing in Corfu, mentions the chimerical Turing program to her new lover, Alexandros. Alexandros is an archaeologist struggling with his current discovery, a mysterious gearbox recovered from an ancient shipwreck near the island of Kythera. After their fevered assignation, Ethel leaves Alexandros heartbroken. He spends the next 200 pages working through the loss while being educated by Turing on a number of computer science and related topics.

The book's subtitle is apt, and the coverage of computing-related topics is daunting. They include non-Euclidean geometry, the liar paradox, Cantor's diagonalization proof, pipelined computer architectures, packet switching, Turing machines, uncomputability, the halting problem, morphogenesis by reaction-diffusion, Arrow-Debreu economic equilibria, NP-completeness, public-key cryptography and the Turing test. Not coincidentally, many of these are core ideas developed by Alan Turing. As the denouement, Turing engages in a Turing test itself: The crucial conversation precipitating the reuniting of Ethel and Alexandros has Turing standing in, Cyrano-like, for the male suitor. In the end, the dangling threads all get resolved—Ethel, Alexandros, Turing, even the Kytherian gearbox.

Perhaps the most attractive thing about the book from the point of view of a computer scientist—and in stark contrast to the vast majority of fiction that deals with computer-related issues—is the quality of the discussions of computing. Typical attempts to make concepts of computer science accessible to a lay readership have a cringe-making quality. Papadimitriou, an acclaimed computer scientist and a professor in the renowned computer science department of the University of California, Berkeley, is not someone to make the kinds of elementary mistakes that one finds in journalistic coverage or garden-variety science fiction. This alone is enough to make a scientist grateful. More, Papadimitriou is, refreshingly, willing to grant the reader some intelligence; he describes the Aegean shoreline as "so hauntingly beautiful because its fractal dimension happens to be equal to the golden ratio" and is willing to stop there, with no pedantic explanations of either of the technical concepts. (Whether the claim is true is a different matter.)

This is truly a novel of ideas, and not only ideas about computer science. The author brings up philosophy, both ancient (more Greek philosophers than anyone outside a philosophy department should be able to name) and modern (Bertrand Russell); history, both distant (Roman Empire) and recent (Edward and Mrs. Simpson), both deep (World War II) and superficial (Edward and Mrs. Simpson); and ideas from mathematics, economics, biology. The breadth of knowledge that Papadimitriou displays is striking, without being overbearing; one is left feeling that a meal with the author would be fascinating, not tedious.

True, the writing gets a bit mawkish at times:

He pauses, he looks deeply into her eyes, then: "All I want now is to be with you, my love. All the time. No masks, no games.”

Jackie Collins is ventriloquized in sex-charged scenes. On the other hand, some of the tropes seem to have come from the oeuvre of William Gibson (the famed science-fiction novelist who coined the term cyberspace):

"If this is true, if he can pick out clients of relevance engines, you know what it means?” Her little face is now full of shadows. "It means that this is runner code, Dad. It means he has taken over the relevance engines, shredded their smoke.”

Or, as Gibson would have it, "cracked their ice."

And, of course, there are plenty of details to quibble about. Indeed, much of the book's afterword, which consists of 36 pages of newsgroup postings attributed to members of a book club reading the novel, is devoted to quibbles on one topic or another: Is the author's presentation of the history of cryptography "timid" in not making clear the conspiratorial role of the U.S. National Security Agency? Did Archimedes really die at the hand of a soldier who erased a diagram the mathematician was drawing in the sand? Is the author too kind to the Macedonians? Not kind enough? This "reader commentary," however, allows Papadimitriou to provide references to the literature and to expand on some of the technical ideas in the text without encumbering its flow.

One of my own quibbles is that Papadimitriou passes on two myths about Alan Turing: that he predicted his eponymous test would be passed by the year 2000, and that he viewed passing as requiring a mere 30 percent probability of confusing the judge in the test. Both claims are based on common misreadings of Turing's seminal paper "Computing Machinery and Intelligence."

But such nitpicking misses the point. The plot, such as it is, provides the excuse to present the most interesting, important and exciting results of computer science, as well as a passel of other ideas, in a readable and entertaining way, with a veneer of romance. This novel is a fun read, but not a mere entertainment. It has profundity as a side effect.