In a certain chess game, White mated in his sixth move by playing gxf8=N. Reconstruct the game!

For people not used to this notation: if we label columns from a (at the left) to h (at the right), there was a white pawn in the 7th row of the g column, that took a black piece in the 8th row on the f column, was promoted to a Knight, and mated the black King.

With a mate originating from gxf8, the g7 field is not under attack after this move (because there is not enough time to bring another piece to that spot).
This means that the King can't be on h8 (He could escape to g7).  Of course he can't be on g8, f8 and e8. 
Then the black King must be mated on d8, and the problem is solved.  In order to get the King on d8, move the black c pawn and let the black Queen occopy its place, then move the King to d8 and then black just has to wait.
These are the moves
1.h4 c6
2.h5 Qc7
3.h6 Kd8
4.hxg7 a6 (or a5, b6, b5,...)
5.gxf8 = N

If it has to be in 6 moves, as the problem states, you can lose some time with moving the pawns on the a and b columns.

Posted by Hugo on 2005-02-25 20:17:32