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Subject: Re: Is the crafty approach to pondering the right one?+suggestion

Author: Robert Hyatt

Date: 15:05:24 05/24/00

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On May 24, 2000 at 10:28:57, Oliver Roese wrote:

>Hi all!
>
>This question is about pondering during the opponents time...
>Crafty does the following:
>It predicts the oppononts move, assuming "optimal" play and then starts to
>work until the opponent moves.
>If it predicts the opponents move correctly it has a great edge, otherwise
>only some hashtableentries.
>If it wouldnt predict the opponents move it would gain a small contribution to
>_every_ move.
>Obviously the better it predicts the opponents move, the better is the first
>method.

Point 1.  Against strong opposition, it correctly predicts about 50% of
the time, roughly.  Which is not terribly surprising...


>From my experience as a mere chessplayer i would say the following:
>-Predicting the opponents move is very difficult even in games of the
>highest value (disregarding trivial cases and extraordinary circumstances).
>-Intuitively i would judge a small contribution to every move as more
>worthfully than an extremly big one that occurs seldomly
>To say it exaggerated: If you have 20 moves to made and distribute
>your resources evenly, you may have a chance. If you invest all in the first
>move, making the other 19 moves very bad, you are dead for sure.
>In more general terms:
>The relative benefit of predicted moves decreases rapidly with increasing
>searchdepth, i think.
>
>Maybe one could use a hybrid approach?
>What is the reason to having this in crafty?

Easy.  At present, about 1/2 of the time it correctly predicts the opponent's
move, and can make a move using little of its own time.  saving about 1/2 of
the total time.  How would you improve on that?  If you pick the best 4 moves,
and searched them equally (during pondering) then after your opponent moves,
you have spent 1/4 of the normal time on the move he played.  You save 25%.
25% is < 50%.  If you pick the best 2, you could save 50% total.  Which is
what it is already saving.



>Thanks in advance for any input and giving me some of your time.
>
>Oliver Roese



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