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Subject: Re: Question about opening book+hash key?

Author: Robert Hyatt

Date: 05:57:43 05/24/01

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On May 24, 2001 at 08:55:15, Pham Minh Tri wrote:

>On May 24, 2001 at 08:14:37, Gian-Carlo Pascutto wrote:
>
>>On May 24, 2001 at 07:50:32, Pham Minh Tri wrote:
>>
>>>Hi,
>>>I heard that the hash technique could apply to opening book. Could someone
>>>explain to me how to use and what is the benefit?
>>>Thank very much in advance,
>>>Pham
>>
>>Quite simple. Instead of storing positions or sequences you store
>>the hashes of the positions.
>>
>>The benefit is space. If you were storing sequences you will also
>>spot transpotions now.
>>
>
>Could you explain more detail? I still do not understand. The 64 bit hash key is
>always bigger than 16 bit of a move representation, and the random numbers may
>make the hash key after moving totally different from the old one, so how to
>save space?
>
>And another question: does this technique need more computing (to match and
>extract) than the normal technique (use other kind of database)?
>
>Thanks,
>
>>--
>>GCP

To build the book, make the first move in the book line, say e4.  Store the
hash signature _after_ that move is made.  Then for other first moves (say d4)
do the same.

When you want to use the book, generate all legal moves, make each one, one
at a time, and after making one, check to see if the current hash signature
matches a signature in the book file.  If so, this move is a "book move".



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