Author: Robert Hyatt
Date: 07:06:35 05/23/01
Go up one level in this thread
On May 23, 2001 at 02:11:06, Pham Minh Tri wrote: > >I would like to make clear on this point. When I use two 32-bit hash values, >they are equal to a 64-bit hash key and work as many other implementations (do >many things with 2 32-bit variants seem to be easier than with 64-bit). The main >different is that I store only _half_ of this 64-bit hash key (store only 32-bit >hash signature). This saves much memory (1/4). However, I am still worrying >about its safety. Does anyone do a test/research about it? > What this means is that you are using "n-bit hashing" where 32 < N < 64. If you use a hash size that needs (say) a 20 bit index, then your value of N is 52 bits since that is the part of the 64 bit signature you are actually using. 52 bits is not bad. Not as safe as a full 64-bit scheme of course. All I know about the safety, from some _long_ tests I ran, is that 32 bits is totally unusable, and 64 is completely safe (has so few collisions they can statistically be ignored).
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.