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Subject: Re: What is evaluation hashing?

Author: Russell Reagan

Date: 10:02:27 08/24/03

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On August 24, 2003 at 08:13:47, Ross Boyd wrote:

>Thanks for explaining it.  I thought it would be more elaborate than this. At
>first thought, I would imagine the normal hash table lookups would make an extra
>eval hash redundant. Perhaps the key to the eval hash is that the returned
>scores are not bounded in any way or tied to a depth and will always be used if
>found.
>
>I guess it would payoff most for really complex/slow evaluation functions.
>
>What size relative to a 64Mb TT would the eval hash be? Any idea?

One example of evaluation hashing is a pawn structure hash table. You can keep a
hash key of where the pawns are on the board, then you can do extensive
evaluation of the pawn structure and hash it, and the next time around you will
get all of that work for "free". This works very nicely since the pawn structure
doesn't change very often.



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