1.
[
{B:1N6/8/K7/3k4/3p3B/p7/2PP4/8}
{V:White to play and win.  Try it on the board.;b8c6;Correct;Incorrect.;In an over-the-board game, the great majority of moves are made without the end of the game being foreseen. A similar attitude is often helpful when solving studies, just try the move that looks best, and see where it leads. In this position, White is well up on material, but Black's advanced a-pawn is on the verge of promotion. Why not use the out-of-play knight to delay the advance of the pawn, and see what turns up?}]

2.
[
The knight sacrifices itself for the sake of a tempo. Using the bishop for same purpose is ineffective, for example 1 Bf6 a2 2 Bxd4 Kxd4 3 Nc6+ Ke4 and White cannot stop the pawn.]

3.
[
{S:b8c6}
1 Nc6!]

4.
[
{S:d5c6}
1...Kxc6
Black must accept, because after 1...a2 2 Nb4+ he loses his only hope.]

5.
[
{S:h4f6}
2 Bf6
Attacking the undefended pawn on d4 holds Black up for another move.]

6.
[
{S:c6d5}
2...Kd5]

7.
[
{B:16/K4B2/3k4/3p4/p7/2PP4/8}
{V:Once again Black's reply is forced, as after 2...Kc5 3 Be7+ he loses the pawn. What is the next step in White's struggle against the a-pawn?;d2d3;Correct;Incorrect.;At first sight White's efforts have achieved little, and he now faces exactly the same problem as in the initial position, only with a knight less. But the position of the bishop on the long diagonal is a new factor, for example if White advances his c-pawn, then ...dxc3 can be met by Bxc3 stopping the a-pawn. How should White prepare the c-pawn push?}]

8.
[
{S:d2d3}
3 d3
White wants to play c4+ without allowing the reply ...Kxc4.]

9.
[
{S:a3a2}
3...a2
The only move. Black's king must guard d4, and 3...Kc5 still loses to 4 Be7+.]

10.
[
{S:c2c4}
4 c4+]

11.
[
{S:d5c5}
4...Kc5
After 4...dxc3 5 Bxc3 White wins by bringing his king back to support his own d-pawn. Now we are at the climax of the study. Black's a-pawn is about to promote with check, but it turns out that while White has been trying to hold back the a-pawn, he has also had a secret agenda to achieve .... what?]

12.
[
{S:a6b7}
5 Kb7!!
Now Black must promote, or else Bxd4 wins.]

13.
[
{S:a2a1}{X:a1}{P:BQa1}
5...a1Q
Answer, checkmate!]

14.
[
{S:f6e7}
6 Be7 mate.]
