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Subject: Re: Evaluation-based Reductions and/or Extensions

Author: Vasik Rajlich

Date: 00:53:10 12/29/03

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On December 28, 2003 at 23:31:21, Tom Likens wrote:

>On December 28, 2003 at 20:54:36, Bob Durrett wrote:
>
>>Your bulletin is exciting since it shows there is still room for innovation in
>>engine design.  As you and others here develop and implement this idea the
>>overall level of play of chess engines will go up simply because the
>>front-runners will be forced to adopt some of your new ideas.  I have often had
>>the suspicion that "current wisdom" regarding searching, pruning, and the like
>>is holding back the truly innovative people who might feel obligated to cling to
>>the old ideas.  I think the whole current theory about "extending and reducing"
>>needs to be re-thought, although I am definitely no authority on that subject.
>>The Earth is not flat after all!
>>
>>Perhaps the next extension of your idea is to perform and utilize complete
>>dynamic position evaluations to refine the searching.
>>
>>Congratulations to you and the others for corageously pursuing a new idea which
>>perhaps may go against "current wisdom."  It is only through original innovation
>>and invention that advances will be made.  Old ideas are not always the best
>>ideas.
>>
>>Bob D.
>
>Hello Bob,
>
>I think you might be underestimating the commercial engines.  My suspicion
>is that they have been using techniques similar to this for years.  From my
>short experience with the idea it's seems obvious that it has a tremendous
>amount of potential but could be getting it right is tricky.  My guess is
>the commercial guys have struck the right balance and are reaping the
>benefits.
>
>BTW, Tord Romstad deserves the credit for starting my neurons along these
>paths.  He's been doing this and more for quite awhile now in Gothmog and
>has been more than willing to share his ideas with anyone that wanted to
>discuss them.
>
>regards,
>--tom

I am quite sure that Shredder is doing some very speculative selective pruning &
extending. It has very high search depths, especially selective search depths -
(12/28) is not unusual in middlegame positions. Furthermore, its nps is not very
high.

This really hit me yesterday when I accidentally started Shredder instead of my
program Rybka in the chessbase GUI and started to wonder why it was reporting
such nice depths :-)

Regards,
Vas




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