## By Bruce Schechter, Simon & Schuster

### The Mathematical Journeys of Paul Erdos

Paul Erdos was a strange but interesting man. He was one of the most prolific mathematicians of the 20th century authoring over 1,500 papers. Seldom holding a fixed academic position, he spent much of his life wandering the world, visiting various mathematical centers and living out of two suitcases. He would often unexpectedly arrive somewhere and signal his readiness to work by declaring: “My brain is open.”

One of the fascinating things about Erdos was his own private language. He called children “epsilons”; friends that had gotten married were “captured”; God was “The Supreme Fascist”. He said that God keeps “The Book” which contains the best and most elegant proofs of all the mathematical theorems. You didn’t have to believe in God to believe in “The Book”. If he saw a proof that he especially liked he would say that “it came straight from The Book”.

Erdos was good at inspiring other mathematicians and most of his papers were co-authored with other people. He had more then 450 co-authors. This, along with the fact that Erdos appeared to be practically non-sexual, led to one of the more endearing stories that Schechter includes in his biography. It seems that although Erdos usually traveled by air, once he took a long train trip across the country. It chanced that he was seated next to a young and stunningly beautiful woman. He struck up a conversation and… well, one thing led to another and by the time they reached Penn Station they had co-authored a mathematical paper!

Schechter weaves into his biography enough of a taste of elegant mathematics so that the book is much more than amusing incidents about Erdos. He gives several simple and elegant proofs which are easy to understand and “straight from the Book.” He gives a taste of combinatoric problems, which was a principal area of work for Erdos. One of his interesting topics is Ramsey theory which shows that in a set of objects it is never possible to have complete chaos without some patterns. Ramsey theory explains why men will always see constellations in the stars. Or why people can shift through the Bible looking for groupings of letters (like every 7th letter) and come up with “prophecies” of current events. Actually, any long book will do, but people are more impressed when it comes from the Bible.

This is an especially wonderful book for any young person interested in mathematics and the wonderful people who work in it. If you know such a person, buy it for him.

Reviewed by David Park