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Subject: Re: SEE for forward pruning in Q. Search

Author: Tom King

Date: 14:09:43 08/05/99

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On August 04, 1999 at 16:56:44, Andrew Williams wrote:

>On August 04, 1999 at 16:32:10, Tom King wrote:
>
>>Hi all,
>>
>>What are the pro's and con's of using a static exchange evaluator (SEE)
>>for pruning captures in the Q. search? My program currently *doesn't*
>>use a SEE, but if I remember right, some programs like Crafty and Ferret
>>use a SEE to prune "losing" captures, i.e they examine a swap sequence on
>>a particular square, and if it appears to lose material, they prune that
>>capture right out.
>>
>>Who else is using a SEE in this way? I was playing around with this kind
>>of thing at the weekend, and I found that pruning these "losing" captures
>>is not without risk - some test problems are solved a ply later than normal
>>(for my program, anyhow, and this could be a bug in my SEE). On the other
>>hand, search speed is increased, sometimes quite dramatically.
>>
>>Opinions? Is pruning SEE losers in the Q. search a win?
>
>I've used it in PostModernist for as long as I've had my SEE. I haven't
>tested it recently, but at the time I included it, it was a clear
>improvement.
>
>Andrew Williams

From the posts I've seen so far, the consensus is that this kind of pruning is a
win. I'll post some test results of my program running throught some test
positions, with and without this SEE pruning.

Cheers,
Tom



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