> As Don wrote, the
> main problem of null move is the depth reduction. It hides long-term
> threats that the evaluation function might not be able to evaluate.
even with a very good evaluation function, i would think that another problem
(this is likely just restating what you and others have already said) is that
your opponent
can quite readily often crush you if you pass, even if he plays what would
otherwise be a fairly substandard move. the sheer advantage of having sente for
free can be huge. at the beginning of the game it's an entire handicap stone,
and near the endgame it can mean several new ko threats. in the middle game
it means winning any reasonable liberty race, turning many reasonable kills into
sekis, blocking any ladder, etc. so it wouldn't, generally, ever generate any
cutoffs,
and yet you'd be checking it with every move for effectively no reason.
there is a related concept that go players actually do use, and it has to do
with reordering a set of moves that have been played to see if it changes the
position. tewari analysis -- this is probably more useful than null-move
pruning,
as it should be able to make a relatively weak evaluation function act stronger.
s.
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