Erdős Number
The Erdős Number is defined inductively. Paul Erdős has Number 0 and someone else has Number n if the smallest Number among his collaborators is n-1. In general, finding an upper bound is relatively easy, but proving such bound is sharp is much more difficult. In my case, an upper bound, discovered with the help of MathSciNet, is 5.
- Vincent Quenneville-Belair coauthored with Burt S. Tilley. DOI
- Burt S. Tilley coauthored with Gregory A. Kriegsmann. MR1952249
- Gregory A. Kriegsmann coauthored with William L. Siegmann. MR0802189
- William L. Siegmann coauthored with David C. Arney. MR1001676
- David C. Arney coauthored with Paul Erdős. MR1431944