Question 83
Consider an $8 \times 8$ chessboard, on which we place some bishops in the 64 squares. Two bishops are said to attack each other if they lie on a common diagonal.
a. Prove that we can place 14 bishops in such a way that no two attack each other.
b. Prove that we cannot do so with 15 bishops.
a. Prove that we can place 14 bishops in such a way that no two attack each other.
b. Prove that we cannot do so with 15 bishops.