Author: Reinhard Scharnagl
Date: 18:23:42 12/23/03
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On December 23, 2003 at 21:12:42, KarinsDad wrote: >On December 23, 2003 at 18:40:03, Reinhard Scharnagl wrote: > >>On December 23, 2003 at 16:35:02, KarinsDad wrote: >> >>>Another point is that you only need 62 bits to indicate piece/pawn location (the >>>position of the kings is already known). >> >>Therefore these two redundant bits are instead used to signal, whether any >>castling is possible with the appropriate king or not. So a continuous bit >>sequence could be preserved without having a two bit redundance. >> >>Reinhard. > >But that is not needed. It's two wasted bits in all positions. > >12 bits for two king locations and all castling information is sufficient. > >A simple way to get all 16 possible castle positions is to use the same space >for both white and black kings. > >For example, wka1/bka1 through wkh1/bkh1 plus wka2/bka2 through wkh2/bkh2. > >None of these state that the white king is on any of those squares, they are >just illegal positions that indicate that the white king is on e1, the black >king is on e8, and oh by the way, the castling state is x. As I have mentioned in another reply, it is not as easy to encode that, because of the fact, that when one king has been moved, castling might still be possible for the other one. Sure, it might be possible to manage this encoding by a 'translation' table, which allows changing illegal kings' positions into special situations with different castling rights. But for me this method seems not to be transparent. Reinhard.
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