What's your Shusaku Number?

Someone on Sensei's Library proposed a Shusaku Number for Go players, similar to the Erdos Number for mathematicians, or like the theory of six degrees of separation (or six degrees of Kevin Bacon in the movie industry).

It works like this. Shusaku, and only Shusaku, has a Shusaku Number of zero. Anyone who personally played him at Go has a Shusaku number of one. Anyone who played one of those people (but not Shusaku himself) has a Shusaku number of two, and so on.

It indicates how close you've come to playing "The Great One" of Go. It's pretty tough to figure yours out exactly, but it makes a good Fermi problem. Let's assume that all professionals play all their contemporaries at least once. I've played an amateur 6-dan, who must have played at least one professional (probably more) in his life to get where he is. I've also played lots of people online, at least some of who must have received a lesson from a pro at one time. Either way, I'm probably one step removed from playing a pro. Now we just need to figure out how many generations of Go professionals there have been since Shusaku died. That was about 140 years ago. Let's say an average Go career is about 40 years. That makes about 4 generations. So modern professionals probably have a Shusaku number of around 4 or 5, which would likely make mine about 6 or 7.

Apparently, the lowest Shusaku number of someone alive recently is 3. This belonged to Iwamoto Kaoru (died in 1999), and possibly a few others who are still alive.

This whole thing seems like something that would only be of interest to geeks, but a lot of Go players are geeks. I'm no exception. And I think it's interesting.