[computer-go] Efficiently selecting a point to play in a random playout

[Jason House]

Don Dailey wrote:
> Lukasz Lew does something far more sophisticated and very fast using the
> concept of pseudo liberties which you might want to look into.
>   

Both pseudo liberties as well as disjoint set chain tracking.  Curiously 
enough, they're both things I independently came up with when I was 
designing HouseBot the first time around, but included neither in the 
open source version.  Pseudo liberties had a very negative response on 
the computer go mailing list at the time, so I chose something closer to 
real liberty tracking.  When I implementing undo's I figured the 
disjoint set stuff was too complex and might scare away developers on an 
open source project (simple, easy to read code is a big plus).  I still 
wonder if I was the original creator of either concept...