If you are one of the lucky mathematicians (there are 509 of
them) who have written a joint paper with Paul Erdös, then
your Erdös number is 1. If you have written a joint paper
with a person whose Erdös number is 1, then your Erdös
number will be 2. And so on.
My Erdös number is 3, because I have written several joint papers (see my papers here) with Ömer Eğecioğlu whose Erdös number is 2, because Ömer Eğecioğlu has written a joint paper with Charles Ryavec whose Erdös number is 1. Charles Ryavec has written a joint paper with Paul Erdös.
The Erdös Number Project studies research collaboration among mathematicians. To find out more about it and possibly discover your own Erdös Number, please go to here.
Çetin Kaya Koç