1.
[
{B:8/7p/6Nk/5p1P/7P/1p3K2/6p/6B1}
{V:White to play and win.;g1e3;Correct;Incorrect.;White has trouble coping with Black's two advanced pawns, so he has to combine maneuvers against the pawns with threats against the Black king. Accuracy is required, however, since 1 Nf4? b2 2 Bc5 is met by 2...g1Q! 3 Bxg1 Qxb1, and Black promotes safely.}]

2.
[
{S:g1e3}
1 Be3+!
Not 1 Nf4? b2 2 Bc5 g1Q! 3 Bxg1 b1Q, nor 1 Bd4? hxg6.]

3.
[
{S:f5f4}
1...f4! 
The best defense, since 1...Kg7 (1...Kxh5 2 Nf4+, followed by 3 Nxg2+ and 4 Bc1, stops the pawns and wins for White) 2 Kxg2 hxg6 3 h6+ Kh7 4 Bc1 f4 (otherwise White just advances his king to g5) 5 Kf3 Kxh6 6 Kg4! is winning, for example 6...Kg7 7 Kxf4 or 6...b2 7 Bxb2 f3 8 Bd4.]

4.
[
{S:g6f4}
2 Nxf4
Black's idea was that 2 Bxf4+ could be met by 2...Kxh5, and now the square f4 is not available for the knight.]

5.
[
{S:g2g1}{D:100}{X:g1}{P:BQg1}
2...g1Q!
Black cannot play 2...b2 immediately, because of 3 Nd3+ and 4 Nxb2, so first he must deflect White's bishop.]

6.
[
{S:e3g1}
3 Bxg1]

7.
[
{S:b3b2}
3...b2
This is the critical moment. Black's counter-play has become serious, but his king is caught in a trap. If you have not already worked out the rest of the study, stop here and try to figure it out. White's most obvious move meets with a cunning defense, but of course White has the last laugh.]

8.
[
{S:g1c5}
4 Bc5
What else? White can no longer stop the pawn, so he has to play for mate.]

9.
[
{S:h6g7}
4...Kg7
The only move to prevent mate, but what about the simple reply 5 Bd4+?]

10.
[
{S:c5d4}
5 Bd4+]

11.
[
{S:g7h6}
5...Kh6!
This is the whole point of Black's defense. Taking the pawn is stalemate, while playing 6 Bc5 is just a draw by repetition. In order to win White has to abandon the mating net with Black's king on h6 and substitute a new one with the king on h4, something which is hard to see for psychological reasons.]

12.
[
{S:f4e6}
6 Ne6!
Now the pawn is threatened, so Black must promote.]

13.
[
{S:b2b1}{D:100}{X:b1}{P:BQb1}
6...b1Q
Black is ahead on material, but White can hunt the enemy king to its doom.]

14.
[
{S:d4g7}{D:1000}{S:h6h5}
7 Bg7+
7...Kxh5]

15.
[
{S:e6f4}
8 Nf4+]

16.
[
{S:h5h4}
8...Kxh4]

17.
[
{S:g7f6}
9 Bf6 mate.]
