Author: Sune Fischer
Date: 15:05:43 12/03/01
Go up one level in this thread
On December 03, 2001 at 17:50:15, David Rasmussen wrote: >On December 02, 2001 at 23:58:43, Robert Hyatt wrote: > >>On December 02, 2001 at 22:38:30, David Rasmussen wrote: >> >>>Many people use 32-bit pawn hashkeys. But I've found that 32 bits is not enough >>>to avoid collisions. 64-bit seems to be enough, and maybe less could do the job. >>>Why do people use 32-bit keys, when it screws up evaluation this way? >>> >>>/David >> >> >>32 is ok for pawns. To see why, figure out how many _different_ positions >>there are with only pawns on the board. The number is not as large as you >>might think, which makes collisions unlikely so long as you _only_ hash pawn >>positions. > >Are you saying that if I'm seeing collisions, I have a bug, or are you saying >that 300 collisions out of 60.000.000 successful probes is not a problem? If the >latter, then why? How can you be sure? > >/David I would say so, 300 collisions is way too high, even if you used a 32^2 entry size table you shouldnt get more than 1 collision per 100 game or so. Using a smaller table will decrease the probability even further. -S.
This page took 0.01 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.