The Erdös Number Project

Mathematics and Science Center, Room 346
146 Library Drive
Rochester, MI 48309-4479
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The Erdös Number Project




The Erdös Number Project

This is the website for the Erdös Number Project, which studies research collaboration among mathematicians.

For reasons beyond our control, this site may soon disappear from this location. However, a new version exists. Please click here to visit the new Erdös Number Project website and bookmark it for future reference. Updates will be made primarily to the new site.

The site is maintained by Jerry Grossman at Oakland University. Please address all comments, additions, and corrections to Jerry at

Erdös numbers
have been a part of the folklore of mathematicians throughout the world for many years.  For an introduction to our project, a description of what Erdös numbers are, what they can be used for, who cares, and so on, choose the “Information about the Erdös Number Project” link below.  To find out who Paul Erdös is, look at this biography at the MacTutor History of Mathematics Archive, or choose the “Information about Paul Erdös” link below.  Some useful information can also be found in this Wikipedia article, which may or may not be totally accurate.


  • The Erdös Number Project Data Files: Lists of all of Paul Erdös’s coauthors and their respective coauthors, organized in various ways.  There are also links to websites of or about Erdös’s coauthors.
  • Facts about Erdös Numbers and the Collaboration Graph: Statistical descriptions of Erdös number data, a file of the sub graph induced by Erdös coauthors, Erdös number record holders, facts about collaboration in mathematical research and the collaboration graph, including some information about publishing habits of mathematicians (for example, the median number of papers is 2, and the mean is about 7).  This subpage has loads of information about the collaboration graph and Erdös numbers, including the distribution of Erdös numbers (they range up to 13, but the average is less than 5, and almost everyone with a finite Erdös number has a number less than 8) and “Erdös numbers of the second kind”.
  • Research on Collaboration in Research: Papers on collaboration in scientific research, collaboration graphs and other small world graphs, and Erdös numbers.  A lot of research is currently being done by various scientists on collaboration graphs and related topics.

I have finished updating all the coauthor lists, and I am slowly putting the new information onto this site. The data are based primarily on all items appearing in MathSciNet and DBLP through mid-2020. About 2600 new people with Erdös number 2 are being added.

You are visitor number since we started keeping track on July 3, 1996, using web counter.

This page was last updated on June 2, 2021. It will not be updated again. Please visit the new version of the project website.