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 way in programming?

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Answer 1

You just want to measure the diameter of the graph. This is exactly the metric to find out the seperation between the most-distantly-connected nodes in a graph.

Lots of algorithms on Google, Boost graph too.