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Subject: Re: Transposition table hash key length question

Author: Uri Blass

Date: 06:29:22 05/31/03

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On May 31, 2003 at 08:52:09, Fermin Serrano wrote:

>Hi Robert:
>   I have ported the code to use 64 bits int. It was near easy. After that the
>problem continue and I have discovered where the problem was. I have to check
>the move retrived from transposition table is valid. I know I have to do this
>for killers, but I am confused in trasposition table (you use a validmove
>routine for transposition table too in crafty). Did not trasposition moves
>retrieve be always correct? why do you apply this routine?
>   Thx in advance.

If a collision is possible then they may be wrong.
This is almost not a practical problem with 64 bits because you may get one
wrong move per year so I guess that you have another bug(maybe bad choice of
your 64 bit numbers) but even after you fix it you should always check if you
use a valid move in the tranposition table because you do not want your program
to crash even if it happens only one time in a year.

Uri



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