Author: Rick Bischoff
Date: 09:25:39 07/29/03
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Hi, While my rate of 118/88570 was indeed high (I had a bug in the zobrist key generation...), the rate you quote (one false match every few days) is way too low!! Hash size is really irrelevant here assuming you store the full 64 bit key in the hash table and only return a move if the keys match (which is what I am doing); Anyway, it is the birthday paradox.. the more keys you have, the better chance there is that at least two of them will share a key. >So 118 out of 88570 times that you thought you had a match from the hash table, >it turned out that not only was it not a match, but the move stored wasn't >even legal. so a false match rate higher than 1 in 750. That is absurdly high. >This is slightly better than I would expect if you were using a 16 bit hash key, >but not much. With a 64 bit hash key, and a large hash table, you should be >getting one false match every few days. The odds of a false match giveing >an illegal move are even worse, since the same move may be legal in many >different positions. > >Angrim
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