Author: Bo Persson
Date: 08:44:48 12/07/01
Go up one level in this thread
On December 06, 2001 at 22:28:20, pavel wrote: >On December 06, 2001 at 17:38:40, Robert Hyatt wrote: > >>On December 06, 2001 at 17:29:43, Severi Salminen wrote: >> >>>Hi >>> >>>How many collisions crafty gets on average using 32-bit keys? So how many nodes >>>Crafty searchs on average to get 1 collision? I'm now using plain Visual C++ 6.0 >>>rand() with no hamming distance tests and I get about 80 collisions out of >>>10'000'000 evaluations from initial position. I'd like to know if that is more >>>or less than Robert and David were seeing. Funny thing was that first I searched >>>about 5'000'000 nodes with no collisions, then I saw 40 collisions in a short >>>time, then again no collisions and finally 40 more in a short time. >>> >>>Severi >> >> >>I didn't compute that number. I simply ran the test with two simple >>mods to the Evaluate() code so that if a pawn position is hashed, the score >>is saved and the EvaluatePawns() code is still executed. If the scores >>and other info don't match after this duplicated work, I produced an error >>and looked at the positions to make sure I didn't have a hashing bug I >>didn't know about. >> >>I was seeing an error 400K-500K nodes, on my PIII/750 laptop, which is about >>one error every 2 to 4 seconds. On my quad (I didn't run the test there as it >>was playing on ICC) this would turn into an error every second or less, which >>is not acceptable. Some positions produced _many_ errors per second, when there >>were fewer pieces so that more pawn moves were being searched... > > >more interesting, atleast for me, to know is that how much does it effect the >game play of the program? Maybe not that much, put it *will* introduce some randomness into the play, which is a really bad thing. How much speed do you gain from using a smaller hash? Murphy's Law indicates that if there is only one random bad move a year, that will happen during the WCCC final playoff. :-) >pavs Bo Persson bop2@telia.com
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