That is a kind of magic, but there have been many gifted individuals in twentieth-century mathematics. Erdős had a more important spell to weave: the Hungarian wizard was quite simply the most prolific collaborator in the history of science. The web of cooperation around the world and across the twentieth century spreads so far it is measured in an honorific unit: the “Erdős number.” People who wrote articles jointly with Erdős himself are said by mathematicians to have an Erdős number of one. Over five hundred people enjoy this distinction. If you wrote a paper with one of them, your Erdős
...more
