ANALYSIS OF ZUGZWANG POSITIONS
Trébuchet positions are usually pawn endgame positions
where whoever moves, loses. It is a “zero game” in that
sense, where none of the players want to play. However,
since chess has “zugzwang”, obligation to move, players
must play the only available moves even if those moves
will bring advantage to the other player.
This position is more complicated, but has the same logic
with trebuchet positions. Here, correct move for white is
Kh1. By playing Kh1, white player creates a “zugzwang”
(obligation to move).
After Kh1, black player has very limited options, and
white player will always have a good move to respond
black player.
If black player plays Kxd4, taking the knight for free,
which seems as the most obvious move, white player can
respond with pawn a6. There is no way black player can
reach white’s pawn, using either the king or the bishop.
In this position:
• If it is white to move, and white player moves
the king, black can respond with the move Kxc4. Black
wins.
• If it is white to move, and white player plays h5,
black can respond with the move gxh5. Black wins.
• Likewise, if it is black to move, and black player
moves the king, white can respond with the move Kxc5.
White wins.
• If it is black to move, and black player plays h6,
white can respond with the move gxh6. White wins.
As shown, white player only needs three moves to
promote his pawn to queen, but black king cannot reach
the pawn if black chooses to play Kxd4. Another way to
understand if a player’s king can reach a pawn is “the
square rule”. The rule consists of creating an imaginary
square with a side that has equal length to distance
between pawn and 8 th row. If the king is in the square,
no matter which player has to move, king can catch the
pawn. If the king is only one square away from being in
the square, king can catch the pawn only if it is king to
move.
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THE CLAPPER 2016 - 2017