Author: Robert Hyatt
Date: 17:11:39 01/13/99
Go up one level in this thread
On January 13, 1999 at 17:48:18, John Coffey wrote: >On January 13, 1999 at 16:58:05, Robert Hyatt wrote: > >>On January 13, 1999 at 12:52:21, John Coffey wrote: >> >>> >>>>as far as 'didn't provide you with all the information you want' that might >>>>be the result of not working with them long enough. I haven't found a single >>>>question I can't answer with bitboards... and many times the question is easier >>>>to answer with them than without... particularly in evaluation where I spend >>>>a bunch of time... >>> >>>I wanted to take into account who controls the most number of squares as a >>>part of my evaluation. Do you think that this can be answered with bitboards? >>>Perhaps some programs already do this? >>> >>>john coffey >> >> >>Most any question you can answer with an offset program I can answer with >>bitboards. I did this early in the development of crafty, but I didn't like >>the result, any more than I liked using "mobility" for pieces. I found other >>scoring terms were more effective and cheaper to compute... > > >The trouble with control of squares is that you have to take into account >the values of the pieces that attack a square. i.e. a pawn could control >a square. I had figured out that I could use bits for each type of piece >that attacked a square, where pawns use high bits and kings use low bits. >Add the bits for each side and the side with the highest number (more or less) >controls the square. there's an alternative type of bitmap you can use here... use a 16 bit short for each square, and designate the 12 right-most bits one for each piece type/ color. Then you can scan your regular bitmap, and build this bitmap which for each square identifies which type of piece (or pieces) attack this square. I don't do this, but there are lots of such ideas if/when you really need that kind of data. I don't use squares attacked stuff at present, other than for move generation...
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.