(The Guarded Chessboard
The White rooks cannot move outside the little square in which they are
enclosed except on the final move, in giving checkmate. The puzzle is
how to checkmate Black in the fewest possible moves with No. 8 rook, the
other rooks being left in numerical order round the sides of their
square with the break between 1 and 7.
Previous: COUNTING THE RECTANGLES.