For those unfamiliar with Erdős -- http://en.wikipedia.org/wiki/Paul_Erd%C5%91s http://en.wikipedia.org/wiki/Paul_Erd%C5%91s -- he was a very prolific mathema

For those unfamiliar with Erdős -- http://en.wikipedia.org/wiki/Paul_Erd%C5%91s http://en.wikipedia.org/wiki/Paul_Erd%C5%91s -- he was a very prolific mathematician whose dedication to his craft was such that he became a vagabond with no home of his own, moving from place to place, living with people who welcomed his visits, offering out-of-pocket rewards for the solution of problems he posed, and remaining very productive for his entire life. Not unlike one's Bacon number, the number an actor receives by working with Kevin Bacon (1), or working with an actor who in turn worked with Kevin Bacon (2), mathematicians have an Erdős number, based on whether one is a co-author with Erdős (1) or is the co-author of a paper along with someone who is a co-author with Erdős (2), etc.. BTW his name is pronounced like "air-dish": http://pronouncemath.blogspot.com/2013/04/paul-erdos-pronunciation.html http://pronouncemath.blogspot.com/2013/04/paul-erdos-pronunc...