Author: Les Fernandez
Date: 18:57:36 10/23/01
Go up one level in this thread
On October 23, 2001 at 17:55:22, Angrim wrote: >On October 23, 2001 at 17:06:14, Dann Corbit wrote: > >>This brings a lot of questions to my mind. If (for instance) we are actually >>representing 262,143 (less illegal) positions, how many wins/losses/draws are >>actually contained in the tablebase file? > >No clue :) but it should be fairly easy to write a program to find out. >just iterate through all of the legal positions and do a tablebase probe. > >>Is the compression based solely on the rotations of the board, or are mirror >>reflections used also? > >reflections are used also, likely exclusively although I havn't >checked Eugene's code. My own code uses only reflections >because they are faster to calculate than rotations. >For a pawnless endgame, there end up being under 500 unique ways >to place two kings on the board without touching. >With pawns, only left-right reflection can be used, which is why the >endgame table with pawns are usually much larger. Hi Angrim, I agree that left-right reflections can be used when pawns are involved unless when you reflect top-bottom you reverse the color of all the pieces and then in turn change the side to move. > >Angrim
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