How can I prove the “Six Degrees of Separation” concept programmatically?

Question

I have a database of 20 million users and connections between those people. How can I prove the concept of \"Six degrees of separation\" concept in the most efficient w

Answer 1

Well a better answer has already been given, but off the top of my head I would have gone with the Floyd-Warshall all pairs shortest path algorithm, which is O(n^3). I'm unsure of the complexity of the graph diameter algorithm, but it "sounds" like this would also be O(n^3). I'd like clarification on this if anyone knows.

On a side note, do you really have such a database? Scary.