Author: Dann Corbit
Date: 10:35:55 07/29/03
Go up one level in this thread
On July 29, 2003 at 13:09:35, Uri Blass wrote: >On July 29, 2003 at 12:25:39, Rick Bischoff wrote: > >>Hi, >> >>While my rate of 118/88570 was indeed high (I had a bug in the zobrist key >>generation...), the rate you quote (one false match every few days) is way too >>low!! Hash size is really irrelevant here assuming you store the full 64 bit >>key in the hash table and only return a move if the keys match (which is what I >>am doing); Anyway, it is the birthday paradox.. the more keys you have, the >>better chance there is that at least two of them will share a key. > >Let assume that you have 2^24 keys. >It means that the probability for collision is 1/2^40 so you may get less than >one collision for 2^40 nodes or one collision in few days. Due to the birthday paradox, with a 64 bit keysize, you will start having to worry about collisions around sqrt(2^64) = 4 billion key stores. If you can do one million NPS (on a fast machine), then about 1000 seconds of search. On an average machine, perhaps one hour of compute time.
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