Author: Robert Hyatt
Date: 11:30:16 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. You have found the fool-proof way of preventing collisions. However, you also see the cost (that of storing a real board position, even if compressed a bit). Bottom line: some errors are acceptable. Searches are going so fast, the probability of a collision is pretty high, but the probability of it happening on a node that is "important" is very low. Which means acceptable.
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