Author: Uri Blass
Date: 05:42:47 12/07/02
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On December 07, 2002 at 06:55:39, David Rasmussen wrote: >In my incremental move generator, I first check if there is a hash move, and if >there is, then I check it for pseudo-legality. If it's not pseudo-legal, I >conclude that there is a hash collision. The position that this move was stored >from cannot be the same as the current, and still they have the same hash >signature. In my program when this happens, I exit. I do this because this >basically never happens. Until now. If you think it never happens then you do not need to check if it is pseudo legal and your program may become faster. All the idea of checking if the move is pseudo legal is for doing something when it happens and not exit(you can simply decide that there is not a hash move and continue the search if you find that the hash move is not pseudo legal) It was playing a game on ICC, and it >suddenly exited. I could see from the log that this is what happened. So I was >wondering: How often does this kind of collision happen for your engines? >I think Bob Hyatt has mentioned that this happens in 1 of 100 games. It doesn't >for me. I think that it is dependent on the size of the hash tables. I expect it to happen more if you use big hash tables. I do not calculate that information. Uri
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