A friend told me about a chess game he had seen. At certain moment, the only pieces on board were a Queen at h8, a Rook at g6, and the Kings at h6 and g8. He didn't remember what color was each piece, but it can be worked out... how?

      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   | K | Q | 8
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |   | 7
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   | R | K | 6
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |   | 5
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |   | 4
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |   | 3
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |   | 2
      +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |   | 1
      +---+---+---+---+---+---+---+---+
        a   b   c   d   e   f   g   h

If the Rook had been at g7, what would have been the colors?

Anyone who knows anything about chess knows that this situation not possibly exist, because both kings are in check. The king at g8 is in check from the rook at g6 and the king at h6 is in check from the queen at h8.

Considering that the Rook and Queen were white, and the King at g8 was black's, this could not exist, for the King is in check from both the Rook, and the King, which of course can not happen because you must move out of check before you attempt anything else.

Similarly, the Queen and Rook cannot be opposing colours, otherwise both Kings would be in check, which is in possible.

The Rook at g6 must differ from the King at h6, otherwise, again, both Kings would be in check.

Assuming that the King at g8 is black, for that is where black's pieces would usually be positioned, the King at g8 would be in check.

Therefore, the situation displayed is a paradox, and impossible to arrive at.

Posted by Daniel on 2004-08-09 00:36:32