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Subject: Re: Crafty is SLOW!!!

Author: Bob Durrett

Date: 05:43:02 09/12/03

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On September 11, 2003 at 21:43:05, Robert Hyatt wrote:

>On September 11, 2003 at 21:19:30, Bob Durrett wrote:
>
>>I have been comparing the top engines [on the same computer] by evaluating the
>>same position, sequentially, with each engine.  Many examples so far, but in
>>every case the time required to get to a given search depth is MUCH longer for
>>Crafty.  Why is that?  Also, does it matter in terms of playing strength?
>
>Why is that?  Different pruning rules.  Commercial programs are doing some
>interesting forward pruning stuff.  The only forward pruning I am using is
>null-move.

I guess the "theory" is that successful pruning [forward or otherwise] is that
time is not wasted in evaluating inconsequential [i.e. irrelevant in the search
for the "best move"] moves and branches.

The "64 Million Dollar Question" is:  "How does a programmer know that his
pruning strategy is good?"  The technical goal of such strategies must be to
decrease the time to reach the correct move while holding the probability of
error to within some acceptable limits.

The answer must be in extensive testing.  Maybe, too, some theoretical
considerations might help with finding the answer.  Perhaps, ultimately, the
answer must be expressed statistically?

Clearly, if a good pruning strategy exists, then the programmer is remiss if
he/she does not find and use it.

Bob D.



>  (I assume you are not comparing junior in this mix since junior
>has a different meaning for "ply" than the rest of us).
>
>
>
>>
>>Could it be that Crafty's findings at depth = 12 are just as good as Junior's
>>findings at depth = 16?
>
>You simply can't compare depths.  IE compare chessmaster to junior and then
>decide which is better based on that.  :)
>
>
>
>
>>
>>If Crafty could find a way to do just as much useful computation in half the
>>time [on the same computer], it would play better.  Right?  [Obviously.]
>>
>>Maybe Crafty 19.03 is wasting too much time on non-essential
>>computations!!!!!!!!!!!!
>>
>>Bob D.



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