Playing chess

Before reading the following, the reader is encouraged to read the introduction to game theory, click here

There are two bizarre chess problems in the following. You do have to know the rules of the game before looking at the problems. For those who do not know the game, please look at here for a quick introduction.

Although these are chess problems, the solutions call more for logical thought than skill at chess.

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Game 1

The problem depicted here was contributed by Dunsany to The Week-End problems book, compiled by Hubert Phillips. White is to play and mate in four moves. Notice that the position is one that could occur in actual play.

Answer:

The key to this chess problem is the fact that the black queen is not on a black square as she must be at the start of a game. This means that the black king and queen have moved, and this could have happened only if some black pawns have moved. Pawns cannot move backward, so we are forced to conclude that the black pawns reached their present positions from the other side of the board!

With this in mind, it is easy to discover that the white knight on the right has an easy mate in four moves.

White's first move is to jump his knight at the lower right corner of the board to the square just above his king. If black moves the upper left knight to the rook's file, white mates in two more moves. Black can, however, delay the mate one move by first moving his knight to the bishop's file instead of the rook's. White jumps his knight forward and right to the bishop's file, threatening mate on the next move. Black moves his knight forward to block the mate. White takes the knight with his queen, then mates with his knight on the fourth move.

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Game 2

This problem is contributed by Karl Fabel, a German chess problemist.

You are asked to find a move for white that will not result in an immediate checkmate of the black king.

Answer:

In the chess problem white can avoid checkmating black only by moving his rook four squares to the west. This checks the black king, but black is now free to capture the checking bishop with his rook.

When this problem appeared in Scientific American, dozens of readers complained that the position shown is not a possible one because there are two white bishops on the same color squares. They forgot that a pawn on the last row can be exchanged for any piece, not just the queen. Either of the two missing white pawns could have been promoted to a second bishop.

There have been many games by masters in which pawns were promoted to knights. Promotions to bishops are admittedly rare, yet one can imagine situations in which it would be desirable. For instance, to avoid stalemating the opponent. Or white may see that he can use either a new queen or a new bishop in a subtle checkmate. If he calls for a queen, it will be taken by a black rook, in turn captured by a white knight. But if white calls for a bishop, black may be reluctant to trade a rook for bishop and so let the bishop remain.

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