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Subject: Re: Two questions about transposition tables

Author: J. Wesley Cleveland

Date: 15:40:58 05/05/00

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On May 05, 2000 at 15:28:55, Mr. Ruben Razquin wrote:

>I found a good example about how to program transposition tables at
>http://www.ics.uci.edu/~eppstein/180a/970424.html . I added a transposition
>table to my program an it works fine, but in some webs about chess programming I
>have found that the data structure for each element of the hash table contains
>one more piece of information: the best move found so far at the moment the hash
>table element was written. Can anyone tell me in which way is that move used and
>how ?
Often a TT hit will not cause a cutoff, but you can search the move that
appeared best last time, which can improve your move ordering, and often you
will not need to generate moves.

>
>Another question. I have started my implementation of transposition table using
>a hash code of 32 bits. How much bits should I use and why?
>
The number of bits determines how often you will get a false match. If the 32
bits are separate from the bits you use to index into the hash table, they
should be enough, as that would be one false hit for every 4,000,000,000 TT
accesses.
>Thank you for your help in advance.



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