Author: Bruce Moreland
Date: 15:30:23 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. 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. It's no better to exit than to crash. You are no less dead if you shoot yourself before the impact. The thing to do in this case is to find some non-awful way to punt. In my programs, I store a move in the hash table, and give it higher precedence when the move generator generates it. If the move generator never generates it, it's as if it didn't exist. There are other obvious ways to handle this. bruce
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