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Subject: Re: Storing AB Bounds for mate scores... what is correct?

Author: Tomasz Michniewski

Date: 23:06:40 05/13/03

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Hello John,

>Usually, a mate score is greater than beta and thus is stored as a LOW BOUND in
>the hash table.
>
>But why? Assuming its the true score, shouldn't it be stored as an EXACT score?
>
>I guess the problem is in assuming it is indeed the shortest mate. Is that why?

I tried storing EXACT instead of LOWER. Unfortunately I found out that my engine
could give up e.g. queen because of returned "mate score" from TT which was just
fail low value (if I remember correctly) from deeper levels and the real mate
didn't exist. It lead to mistakes. That's why I changed it to normal LOWER flag.

I hope it helped a bit. :-)

Best wishes,
Tomek



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