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Subject: Re: A few hashing questions.

Author: Severi Salminen

Date: 14:03:00 12/02/01

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>Two things.  First, if your pawn structure evaluation is pretty simple, hashing
>may be a loser for you.  Because you update the signature on every pawn move,
>but only evaluate pawns at endpoint positions.  If the signature update adds
>up to more "cost" than the evaluation it replaces, you lose some.

Yep, this seems to be the case: too simple to gain anything from hashing. It
helped a little to use 32-bit key instead of 64-bit. But overall it seems that I
have to wait until my pawn evaluation is more complex. Or then I'm so excellent
programmer that my algorithms are so fast that no need for hashing :)

I might try to add some pawn island evaluation to see how it affects - it should
narrow the gap. Also I noticed that on my slow (300MHz) computer, even a table
of 65536 entries is enough. If I perform a 11 ply search in position after 1.e4
e5 2.d4 d5, my pawn hash table still has about 10000 empty slots. Is this too
low? The hit rate was about 96%. After 9 ply search the table was less than
half-full. I allways replace an entry when there is no hit.


Severi



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