Author: Jeff Lischer
Date: 08:34:34 08/01/05
Go up one level in this thread
On August 01, 2005 at 11:19:54, Tord Romstad wrote: >On August 01, 2005 at 10:30:29, F. Huber wrote: > >>On August 01, 2005 at 10:18:44, Tord Romstad wrote: >> >>>On August 01, 2005 at 10:07:49, Andreas Stabel wrote: >>> >>>>Chess 960 is really chess 480 since half the positions are mirror images of >>>>other positions and therefore funtionally identical. >>>> >>>>I do not understand why these mirror positions have not been eliminated. >>> >>>Because they are *not* functionally identical. Castling is not symmetrical. >>>When castling queenside, the king ends up on c1/c8, when castling kingside, >>>the king ends up on g1/g8. >>> >>>Tord >> >>Well, I would say it _is_ identical, if you simply swap the meaning of O-O and >>O-O-O. It´s almost the same as e.g. 1.a4 would be 1.h4 in the ´mirror´ game, >>so it´s only a matter of naming conventions. > >No, it is not. O-O and O-O-O cannot be considered equivalent, no matter how >you look at it. The king ends up on the knight file in one case, on the bishop >file in the other. All the 960 different starting positions *are* >fundamentally different. There is no way to reduce it to 480 positions. > As a concrete example... In the normal starting position the king moves 2 squares when castling either kingside or queenside. Now consider the "symmetric" position with the king and queen locations swapped. Now the king moves 3 squares for O-O and only 1 square for O-O-O. >>What I am really wondering about is, why the restriction "king between rooks" >>has been kept? Without this restriction (and by simply making a little >>modification to the castling moves) there would be much more starting positions. > >Don't ask me. I didn't invent the game, and I've never really understood >the point of it. I suspect maximising the number of starting position wasn't >considered an important goal (and why should it be?). > >Tord
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