RE: computer-go: unmake move?

[Peter.Smith@xxxxxxxxxxxxxxxx]

Hello Bryan.

My data structures are probably nothing like yours, but I only change what's
equivalent to your group number when merging groups.  I also maintain undo
information (as you're probably doing.)

I have the impression in my own code that checking for superko is more
costly than undoing moves.

Regards,

Peter Smith.

> Hi everyone.  This is my first post, and I have a question about
> implementation of a method.  I am using minimax alpha-beta 
> and am trying
> to develop a fast unmake move method.  I am stuck, however, 
> because my Go
> program uses data structures GROUP and INTERSECTION where one of the
> elements of INTERSECTION is the group number of that piece.  
> In trying new
> moves, groups are restructured, requiring me to re-assign 
> group numbers
> all the time.  To make matters worse, during the unmake move 
> for minimax,
> I will have to re-assign group numbers when removing a piece from the
> board causes group structures to change.  This will have a 
> drastic effect
> on the speed of the minimax search, and I'd like to avoid it if
> possible.  Has anyone run into this, and if so, do you have 
> suggestions?
> 
> Thanks very much,
> Bryan McQuade
>