Author: Pat King
Date: 09:17:03 09/22/98
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On September 22, 1998 at 08:50:53, Pat King wrote: >The odds of a search not containing a mistake are therefore >(1-2^-32)^n, where n is the number of nodes searched. To >have a 50% chance of an error, you'd need to search about 3e+09 >nodes. With null-move, that's about 20 plies. He (I) also said >PS Since 1-2^32 is so close to 1, there's probably a fair amount >of error in that 3e+09 estimate, but you can stand a LOT of error >in this case and still have the argument hold up! Well, upon pondering the problem I made a refined estimate (but still only an estimate) of 2^32 or about 4.3 e+09 nodes, which works out to 20.2 plies instead of 19.something. Is the 2^32 figure for P(lookup error)=.5 for a 32 bit key a coincidence? I suspect not. If not, then you can easily decide on how much error you're willing to tolerate. Based on this analysis, 64 bits certainly seems like overkill to me. Pat
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