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Subject: Re: Hashing in distributed perft

Author: Steffen Jakob

Date: 06:03:15 12/19/03

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On December 19, 2003 at 08:29:00, Uri Blass wrote:

>>>If you use pseudo-random numbers for zobrist hashing it is always possible to
>>>get a collision. Yes, this is paranoid. :-)
>>
>>No need to use pseudo random numbers.
>>
>>It is possible to store all the board with 192 bits easily as was explained in
>>another post.
>>
>>Uri
>
>Here is the relevant post.

This encoding is not appropriate for being used as a hash key. You have these
192 bits. To get the index into the hash table you filter some of those bits.
With the encoding of the posting which you mentioned it is very likely that a
lot of similar positions are mapped to the same index. Therefore you will not
use the hash table in an efficient way. It will be efficient with zobrist
hashing.

Greetings,
Steffen.



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