[computer-go] rotate board

[Jacques Basaldúa]

Don Dailey wrote:

> You can use Zobrist hashing for maintaining all 8 keys incrementally, 
> but you probably need a fairly good reason to do so.     Incrementally
> updating of 1 key is almost free, but 8 might be noticeable if you are
> doing it inside a tree search or play-outs.   

Yes. Don is right. Of course that is not part of the real program, but 
of a program that searches the book. In my case (19x19 only) I play a
maximum of 20 moves (10 per player) from the book and then switch to 
the "real" program.

I never shared the naif idea that some openings (played by high dan) are
better than others and that finding a correlation between a given move
and the result of the game was meaningful. I consider all "popular"
openings equally balanced and playable. Finding a move in the book
just saves you the time of 4-5 moves (10 if you are really lucky), gives
you a straightforward way to randomize the opening (drawing between all
moves in the book uniformly) and makes the board contain some information 
when the real thing starts.

Jacques.