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Subject: Re: Let the king capture or generate legal moves

Author: Reinhard Scharnagl

Date: 11:30:01 11/20/04

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On November 20, 2004 at 13:56:24, Michel Langeveld wrote:

>On November 20, 2004 at 12:05:16, Reinhard Scharnagl wrote:
>
>>Hi Michel,
>>
>>I think it does not matter, where you are investing the effort to check the
>>legality of a move. You can do it by making a move or by testing its before.
>>I test it before I move, thus the last ply is not moved. I think it has not
>>that influence you supposed, because if I would make a unecessare move in
>>the last ply I could have ommitted my legality checking parts of the program.
>>
>>But if you would think I am interested in fast results by using some tricks:
>>
>>a) I would not have made a detailed move type statistic (about 20% of run-time)
>>
>>b) I would have posted following results:

>:-) Yes, very nice made with hashing of perft values.

>Do you use a 64bit hash-id of the position or the complete position as hashid?
>The former is not so safe to use. But you probably know that.

I use a 64 bit hashing system. Hashing is never 100% secure. But the positions
are not chosen randomly but interdependent with xoring a limited number of
position depending piece keys beginning at the starting position. Thus the
chance of misfetching data is practically zero until move 64 (if you would
use a special subset of random-number-keys like I do).

Reinhard.



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