Author: Bruce Moreland
Date: 11:39:54 01/14/98
Go up one level in this thread
On January 14, 1998 at 14:04:53, John Bartkiw wrote: > > Just a question for anyone. I've noticed most people are using a >table of random numbers to use instead of the actual bitboards. Can >someone give me the reasoning for this? Is it do to the sparseness of >the bitboards? If you use a key that is derived from the position somehow, you might have similar keys for similar positions. In chess, the board doesn't change very fast, so you tend to deal with big wads of similar positions. The logic behind assigning a random value for each color and type of piece on each square, is that when you move a single piece from one square to another, you will tend to get a hash key that is very distinct from what you had originally. You want it to be as distinct as possible so your hash indexes don't clump up. If they were to clump up, you would beat the tar out of one small chunk of your hash table, while leaving the rest of it empty. You use a random key to generate as much entropy (disorder) as possible, so you use your hash table as efficiently as possible, so you get as many hash table hits as possible. bruce
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.