The Man Who Loved Only Numbers

First things first: The first half of Paul Hoffman’s book is truly excellent. He recounts the life of mathematical wizard Paul Erdös, in a way that is both moving and gripping. This strange man, who would knock on fellow mathematicians’ doors in the middle of the night, crash for two weeks while performing mathematical magic, and then leave all of a sudden, is so well presented that you are saddened that you did not get to meet him.

But perhaps you did? One of the many legacies of Erdös is the Erdös factor, which specifies how close any person has worked with him. If you have an Erdös factor of 1, you published a paper with him personally. If you have an Erdös factor of two, you published with someone who had published with him. However, if you never wrote a mathematical paper with anyone with an Erdös factor, you probably have an infinite Erdös factor (tough luck). And so on.

The theme of the biography is Erdös’ search for mathematical truth. He was obsessed with writing papers, and authored or co-authored a whopping 1,475 of them during his career, with a total 485 co-authors. Among his most interesting works were papers on prime numbers and resolutions to many classic problems, like Fermat’s last theorem (which he didn’t solve).

Paul Hoffman writes with passion. He manages to build tension, and resolve, it as if he were writing crime. The average reader should have little problems following his explanations of the mathematical problems raised and solved by Erdös. This makes for fun reading, and could well have made this one of the best popular science books on mathematics I have read in a long time.

But then he diverts. The bulk of this otherwise excellent book strays so far off the path that it is hard to see what happened. But - hopefully - in order to make sure the reader understands everything, Hoffman presents the history of so many of the math problems, that Paul Erdös disappears, and the beauty of his person with him. I may be unfair here, because most readers may be unfamiliar with Pythagoras, Cantor, Fermat, Fibonacci and other famous mathematicians, and can appreciate a brief introduction. But Hoffman lets these stray paths turn into highways.

The worst example is the story of Ron Graham, in a chapter numbered 'Pi'. Although this is excellent writing, presenting an exhilarating story about one man’s quest for what is labelled 'worst case scenarios', it is so frustrating to read! Putting a foreign chapter with 35 pages about something completely different in the middle of a book, does not make for good composition.

"It would perhaps be more fitting to reorganize the book and call it a collection of essays"

It is like a commercial break - you hate it, but the show won’t start until the sponsors have had their time. Hoffman underlines the point himself by even breaking up this chapter again, with a passage about Fibonacci numbers. And then he goes on and on, each page taking the reader further away from the lovable Paul Erdös, until he all of a sudden comes back to die in the end (as any tragic hero must). It would perhaps be more fitting to reorganize the book and call it a collection of essays.

And that is perhaps the main problem with this book - the focus is all wrong. If Hoffman had maintained his biography all the way throughout the book, without having to fall for the temptation to write the history of every possible math problem in his protagonist’s path, this would be a very good book indeed.

Yet, although Hoffman shoots his own story in the foot, it is difficult not to recommend this book. It is a great read, but be warned that you will spend plenty of time cursing at the writer for showing you a picture for a few seconds, only to make you listen to the entire history of photography for a day or two.

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