A bit of geekish miscellany.
Erdős was an extremely well published mathametician, who loved to collaborate. An Erdős number is the measure of the shortest path between you and Erdős in terms of published papers. Erdős is the only person with an Erdős number of 0. People who coauthored with him have number 1. And so forth.
For what it is worth, I have picked up an Erdős number of 4, without even going to E-Bay.
Ed Dawson is reported to have a Erdős number of 3 giving me a 4 through the publication of the article SKMA – A Key Management Architecture for SCADA Systems