1.
[{B:7k/1R5P/8/8/5P2/3B1Q2/8/2K5}
{V:White to play and mate in three.  Try your solution on the board.;b7b1;Correct;
Incorrect.;The first move must be with the rook, in order to lift the stalemate. The key is to find the right square, but this is not obvious until you have found White's second move. So try a random move, such as 1 Rb3, forcing Black to reply 1...Kg7. Now how should White continue? After White moves the rook and Black replies 1...Kg7, White should play 2 Qb7+. Black's main replies are 2...Kf6 and 2...Kh8. Which is the only square for the rook which allows White to cope with both these replies?}]

2.
[{B:7k/1R5P/8/8/5P2/3B1Q2/8/2K5}
{D:100}{S:b7b8}
Try 1.Rb8+?
Problems in less than six moves very rarely begin with a check, which should be a warning signal that this is not correct.  1...Kg7  2  h8=Q+   Kf7  and there is no mate.]

3.
[{B:7k/1R5P/8/8/5P2/3B1Q2/8/2K5}
{D:100}{S:b7g7}
Try 1.Rg7.
Almost everybody tries this move, but it cannot be better than a 'nothing' rook move such as Rb3, and as problems have only one solution, 1 Rg7 cannot be correct.  1 ...Kxg7 and there is no mate in three.]

4.
[{B:7k/1R5P/8/8/5P2/3B1Q2/8/2K5}
{D:100}{S:b7b1}
1.Rb1!
Why here and nowhere else? The reason only becomes apparent after 1... Kg7  2  Qb7+.  This is the right way to close the net around Black's king.  Now 2...Kf8 and 2...Kh6 are met by 3 h8Q mate and 2...Kf6 by 3 Rb6 mate (this explains why 1 Rb8+ didn't work; the queen would block the rook and prevent it returning to b6). Finally  2...Kh8 3  Qb2  mate. And now we can see why, paradoxically, the rook had to go all the way back to b1.]
