Author: Sune Fischer
Date: 03:52:32 09/26/01
Go up one level in this thread
On September 25, 2001 at 23:57:33, Robert Hyatt wrote: >On September 25, 2001 at 11:33:51, Antonio Dieguez wrote: >>>Note that I don't sign on to the theory that more ram increases the probability >>>of a collision. >> >>Try it yourself, then. With different hashtable sizes. >> >>this is what I got in the initial position, with 16 bits total. With replacing >>scheme always replace. >> >>with 128 entries: >>[9] 978059 nodes, illegal moves=2416 >> >>with 256: >>[9] 909888 nodes, illegal moves=3113 >> >>512: >>[9] 944380 nodes, illegal moves=5450 >> >>1024: >>[9] 847469 nodes, illegal moves=9062 >> >>2048: >>[9] 915317 nodes, illegal moves=15875 >> >>4096: >>[9] 1183890 nodes, illegal moves=38123 >> >>I think it will be obviously the same trying others positions too. What a beautiful experiment Antonio;) >But what if you use a 64 bit key, with absolutely no hope of searching >1/4,000,000,000th of that search space? How many collisions then? And >if you increase the hash size, how many collisions then? He would get the same result: double hash -> double number of collisions. Of couse the actual count would be zero unless it ran for a very long time. >I don't think the experiment is framed correctly to answer the question that >is being asked: "With today's hardware, and 64 bit hashing, is a bigger hash >table always better?" The answer is still yes, IMHO. Yes, I agree completely, but this thread sort of turned into a discussion of whether or not doubling the hash size would also double the probability of a collision. It's the apples and oranges again, we agree on the apples, it was the orange debate that was interesting ;) -S.
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