a) White to mate in one.
b) White to mate in one.
c) White to mate in two.
d) White to mate in four.
Solutions: a) N-g7 mate b) N-f7 mate c) Q-g8ch, RxQ followed by N-f7 mate
d) The immediate Q-g8ch will not work in this case, since black can take the queen with the king instead of the rook. Instead, white must first play N-f7ch, K-g8, then N-h6ch, K-h8. Now white can play Q-g8ch. The rook has to take the queen as the king cannot put itself into check, and now, finally, N-f7 mates!