Erdös Number

We all hear about different types of numbers in Mathematics- even ,odd,prime,real,complex numbers etc. Recently I hear about a different category of numbers called erdös numbers. I came to know about this during the presentation of reading and reflection session by sruthi on the book-'The Man Who Loved Only Numbers' by Paul Hoffman.

The Erdös number describes the collaborative distance between mathematician Paul Erdos and another person,as measured by authorship of mathematical papers.Erdös was an Hungarian mathematician who in latter part of his life spent a great deal of his life spent a great deal of time writing papers with a large number of colleagues,working on the solutions to outstanding mathematical problems.He published more papers during his lifetime than any other mathematician.

The idea of Erdös number was originally created by his mathematician friends as a tribute to his enormous output.Later it gained prominence as a tool to study how mathematicians cooperate to find answers to unsolved problems. To be assigned an Erdös number,someone must be a coauthor of a research paper with another person who hasa finite Erdös number.Paul Erdös has an Erdos number of 0;anybody else has Erdös number is k+1 where k is the lowest Erdös number of any coauthor.Several studies shows leading mathematicians tend to have particularly low Erdös number;the median Erdös number of Fields medalists is 3.For ex: Ramanujan has Erdös number only 3 (thorough G.H.Hardy who has Erdös number 2). Erdös number has significance in other fields:- Physics,Biology,Finance,Economics,Philosophy,law,Engineering etc with scientists in these fields with Erdös number between 2 and 6.