Author: Jesus de la Villa
Date: 10:38:19 01/14/00
Go up one level in this thread
On January 14, 2000 at 00:55:43, Frank Schneider wrote: >On January 14, 2000 at 00:47:11, Tom Kerrigan wrote: > >>'^' is the logical XOR operator in C. >> >>It has the interesting property that (A ^ B) ^ B = A. Example: >> >>12345 ^ 6789 = 10940 >>10940 ^ 6789 = 12345 >> >>To come up with a "unique" number for a particular chess position, you can do >>the following: >> >>unique_id = 0 ^ black_rook_on_a8 ^ black_knight_on_b8 ^ ... >> >>Where black_rook_on_a8 is a random (but constant) integer. Now, because of the >>property mentioned above, you can easily update this unique ID when a piece is >>moved. Let's say you move the rook from a8 to a7: >> >>unique_id = unique_id ^ black_rook_on_a8; >>unique_id = unique_id ^ black_rook_on_a7; >> >>The benefit is that you can hash up this unique ID and use it to index a hash >>table. >> >>-Tom >Yes, I think everyone does it like this and it works great. >Be careful that your numbers are long enough - use 64bit to >make sure you don't get collisions. 32 bit is not enough - do you know the >'birthday paradoxon'? > >Frank > No, can you tell me ? > >> >>On January 13, 2000 at 21:43:09, Antonio Dieguez wrote: >> >>>hi!, I would like to know what is Zorbist? how it works? >>>and what does '^' does? >>> >>>Thanks.Am sorry my foolish questions... >>> >>>me.
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.