Saturday, March 27, 2010

Erdős numbers

Say what...Erdős numbers? It', a mathematical attempt at humor.


The Erdős number...describes the "collaborative distance" between a person and mathematician Paul Erdős, as measured by authorship of mathematical papers.

It was created by friends as a humorous tribute to the enormous output of Erdős, one of the most prolific modern writers of mathematical papers, and has become well-known in scientific circles as a tongue-in-cheek measurement of mathematical prominence.

Paul Erdős was an influential and itinerant mathematician, who spent a large portion of his later life living out of a suitcase and writing papers with those of his colleagues willing to give him room and board. He published more papers during his life than any other mathematician in history (at least 1400).


Bill Ashworth [Linda Hall Library Newsletter] wrote...

Paul Erdös, a Hungarian mathematician, was born Mar. 26, 1913. Brilliant and eccentric, Erdös travelled the world for sixty years with all his belongings in a single suitcase, living off the indulgence of friends and colleagues. If you were a good mathematician, the odds are that one day Erdös would show up on your doorstep with his suitcase and ask for board and lodging. As payment, he would offer to collaborate on a paper or two. When the well ran dry, he would move on to the next household. In this way, Erdös collaborated with over 500 mathematicians and published more papers than anyone in history. As the legend (and the series of publications) grew, a mathematician in 1969 dreamed up the idea of an " Erdös number" as a humorous measure of mathematical eminence. If you wrote a paper with Erdös, you have an Erdös number of 1; there are at least 500 such people, although they are all theoretical mathematicians and you probably would not have heard of any of them. If you did not collaborate directly with Erdös, but you wrote a paper with someone who did, you have an Erdös number of 2. Since many mathematicians write papers with physicists and biologists, there are a few familiar scientists with an Erdös number of two. And if one of these then collaborates with yet another author, that author has an Erdös number of three. And so it goes. It is sort of like the six degrees of Kevin Bacon game, except that you run out of mathematicians before you get to Erdös number 3, and of scientists before you get much beyond 5. In case you were wondering, Albert Einstein and Freeman Dyson have an Erdös number of 2; Richard Feynman, Hans Bethe, and Enrico Fermi have an Erdös number of 3, and those with an Erdös number of 4 include Stephen Hawking, Carl Sagan, Linus Pauling, and, yes, even Bill Gates.

Paul Erdős

The Erdös Number Project

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