Standpat and check

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vladstamate
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Standpat and check

Post by vladstamate » Sat Feb 06, 2010 6:20 pm

Hi there,

How should I deal with stand pat score calculation in quiesce search, in the situation where we are in check? Evaluations while in check are not reliable. So I cannot raise alpha or return beta (I have a fail-hard algorithm) based on the standpat score.

So what do I do with it?

Regards,
Vlad.

jwes
Posts: 778
Joined: Sat Jul 01, 2006 5:11 am

Re: Standpat and check

Post by jwes » Sat Feb 06, 2010 7:09 pm

vladstamate wrote:Hi there,

How should I deal with stand pat score calculation in quiesce search, in the situation where we are in check? Evaluations while in check are not reliable. So I cannot raise alpha or return beta (I have a fail-hard algorithm) based on the standpat score.

So what do I do with it?
If you know you are in check, just extend and ignore (or not calculate) the stand-pat score. Otherwise, you can do an expensive incheck() or an unreliable evaluate(). You can test to see which works better for you.

vladstamate
Posts: 161
Joined: Thu Jan 08, 2009 8:06 pm
Location: San Francisco, USA
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Re: Standpat and check

Post by vladstamate » Sun Feb 07, 2010 5:53 pm

Right,

That was good advice. I just did that in quiesce search: if in check, do not return beta or change alpha based on stand pat score and try to also generate the moves that takes us out of check, not only captures.

That improved the engine noticeably. Plisk went from 400 to 427 in the 9 STS tests.

Thanks,
Vlad.

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