Re: computer-go: unmake move?

[Don Dailey <drd@xxxxxxxxxxxxxxxxxxxxx>]

> String tactics is fast since the evaluation is just the
> number of liberties.  Stable is 5 liberties, and captured is
> zero.

I do this too, but I don't do it very well.  I'm  not sure which moves
to cover.  I consider all moves to the  liberties of the target string
and have some simple stopping rules to  try to control  the search.  I
include some  moves that attack the  opponent if it's  relevant to the
target string.  I can  find ladders and the  thing does work, sort of.
I also test  for trasnpositions.   I  call the routine  twice for each
string.  I believe what  I'm doing is fairly  standard, but I know  my
implementation is  broken in  the sense that   I'm including too  many
moves.

Is there a good description of how this might be done somewhere?  I am
sure I don't have it right.

I had  always thought that programs  do some static evaluation  in the
tactical search to  avoid the blowup  and that  that is  what is wrong
with my routine.   I can imagine that  there might be  ways, with some
kind of simple (or not  so simple) analysis,  to find out that further
searching is  futile for this  tactical string search.  I just haven't
figured it out.

Don