Author: Dan Newman
Date: 14:04:23 09/16/00
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On September 16, 2000 at 12:25:27, Larry Griffiths wrote: >I have tried using a 64-bit hash key and storing it in each hash entry to insure >that different positions that point to the same hash table entry can be >verified. > >I also have a 32 byte smallboard that I use for debugging. This smallboard has >4bits for each piece color and type so I know for sure if the current position >matches the hash table entry. > >The 64-bit hashkey works most of the time, but sometimes different board >positions produce the same hash-key. > >Is there a fail-safe method other than my 32 byte smallboard for insuring that >different board positions with the same hash keys can be resolved? > >Larry. I once tried to measure the error rate and got no errors at all with 64-bit hashcodes over several hours of testing. I was able to measure the error rate for 32-bit hashcodes--that was about 1 false match/second (at perhaps 100k probes/s). I think someone came up with an estimate of (very approximantely) one error/day with a 64-bit hashcode at 100 knps--or was it 1 Mnps? Anyway, the error rate is very low and can mostly be ignored. I do try to make sure that such an error won't crash my program though... -Dan.
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