Author: KarinsDad
Date: 15:09:25 02/19/99
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On February 18, 1999 at 17:04:14, Dann Corbit wrote: >On February 18, 1999 at 14:45:59, Inmann Werner wrote: >[snip] >>What does this mean in particular for chess programming? >> >>I use one hashingadress between 0 and 2000000 for the hash adress and one >>extra calculated long int for verification. Each of the both hashcodes result >>out of 2 different sets of 64 long int numbers. >>How high is the probability of a collision in this case, and do you use the >>same algorithm? >I think we have to know what hash we are using in order to talk about >collisions. For instance, I could choose a hash for people's names which uses >the first six letters as base 26 numbers. This would probably be a rather bad >hash, because people's names are not spelled at random, and because we are >likely to receive them already in order (unless, for some reason we *want* >collisions). >It seems that most chess programs use Zobrist hash. I think it would be >interesting to count collisions for opening, early middle game, mid-game, >endgame, and late-endgame and see if the proportion stays the same as the board >clears. I am fairly sure that it will not be exactly as probability would >dictate if we had a perfectly random distribution of positions. It might also >be interesting to investigate the properties of other hashing algorithms. I have been wondering if changing the Zobrist hash from a set of random number to a set of non-random and very specific numbers could result in a more even distribution in the hash table. Has anyone done any work in this area? KarinsDad
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