Question 29
Determine the largest number of bishops that can be placed on an $8 \times 8$ chessboard so that no two bishops are on the same square and each bishop is threatened by at most one of the other bishops.
Note. A bishop threatens another one if both are on two different squares of the same diagonal. The diagonals of the board are the $2$ main diagonals and the lines parallel to them.
Note. A bishop threatens another one if both are on two different squares of the same diagonal. The diagonals of the board are the $2$ main diagonals and the lines parallel to them.