Ending Challenge

White to move. Is this a win, loss, or draw for white. This requires considerable effort and deep calculation.

7k/1p4p1/3p4/3p3P/7P/2P2P2/8/6K1 w - - 0 1

Comments
No. 1-12
Yancey_Ward
Yancey_Ward

Editor

Well done, Alena.

Alena
Alena

The two lines differ by the position of the pawn. It's very important because the pawn plays a key role.
In the first line the pawn guard f6 and the white king can't come near it and catch the pawn.
In the second line the pawn doesn't guard f6 and the white king come and grab the pawn.

V-1

10.Kc6 Kxc4
11.Kd6 Kd4
12.Ke6 Ke4
13.Kf7 g5
The position is lost for white.

V-2

11.Kc6 g5
12.Kd6 g4
13.c5 g3
14.c6 g2
15.c7 g1=Q
16.c8=Q
It's a draw

V-3

11.Kc6 Kxc4
12.Kd6 Kd4
13.Ke6 g5
14.Kf5 g4
15.Kxg4
It's a draw

V-4

11.Kc6 Kxc4
12.Kd6 Kd4
13.Ke6 Ke4
14.Kf6 g5
15.Kxg5
It's a draw.

I'm looking forward to your next puzzles.

Yancey_Ward
Yancey_Ward

Editor

Alena, consider the following, representative lines:

1.Kf2 d4
2.c4 Kh7
3.Ke2 Kh6
4.Kd3 Kh5
5.Kd4 Kh4
6.Kd5 Kg3
7.Kd6 Kf3
8.Kc7 Ke4
9.Kb7 Kd4 Position after 9 moves is 8/1K4p1/8/8/2Pk4/8/8/8 w - - 0 1

Versus:

1.h6 g6
2.Kf2 d4
3.c4 Kh7
4.Ke2 Kh6
5.Kd3 Kh5
6.Kd4 Kh4
7.Kd5 Kg3
8.Kd6 Kf3
9.Kc7 Ke4
10.Kb7 Kd4 Position after 10 moves: 8/1K6/6p1/8/2Pk4/8/8/8 w - - 0 1

Can you demonstrate and explain why these two final positions are different? These two positions in these lines represent the real principle underlying this beautiful Ryabinin study. Why does white lose the first one, but draw the second? At a glance, it appears to make no sense, right, but when you study them in detail, the reason becomes clear.

Alena
Alena

V-2

1.h6 g6
2.Kf2 d4
3.c4 Kh7
4.Ke2 Kxh6
5.Kd3 Kh5
6.Kxd4 Kxh4
7.Kd5 g5
8.Kxd6 Kg3
9.Kc7 Kxf3
10.Kxb7 g4
11.c5 g3
12.c6 g2
13.c7 g1=Q
14.c8=Q
It's a draw.

V-3

1.h6 gxh6
2.Kf2 d4
3.c4 Kg7
4.f4 Kf6
5.Ke2 Kf5
6.Kd3 Kxf4
7.Kxd4 b6
8.Kd5 Ke3
9.Kxd6 Kd4
10.Kc6 Kxc4
11.Kxb6 Kd4
12.h5 Ke5
13.Kc5 Kf5
14.Kd5 Kg5
15.Ke5 Kxh5
16.Kf5
It's a draw.

Yancey_Ward
Yancey_Ward

Editor

So, where did the extra tempo come from? Black can, of course, just reply with 1. ...g6 rather than capture at h6 with the pawn, thus leaving the fundamental structure of the king side unchanged- the black king can still march and clean up the h-pawns, the g-pawn is still a g-pawn, the white f-pawn is still the same distance from the black king, and black can still play d4 in response to Kf2. Consider comparing the positions that arise in your first line and those that arise after 1.h6!! g6 2.Kf2 d4 etc.

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