Tricky Endgame Composition

Can you figure out white's only winning first move in this position? Can you explain it?

8/5K2/4p3/8/1k6/p7/P1P4P/8 b - - 0 1

No. 1-5
Yancey_Ward

Editor

I meant "forcing the queen off the b-file".

Yancey_Ward

Editor

Exactly- whenever the queen approaches on the b-file- the black king retreats to a1 forcing the queen off the a-file again to avoid the stalemate, but then white never has the free moves to bring the king forward. Well done.

Alena

In the first variation the presence of the black pawn plays a key role because if there is no black pawn it's a draw. As the a-pawn is a rook pawn therefore the black king just sticks to it and the white can't make any progress.The black also has an extra move because of the black pawn and the black can't use a stalemate if the queen gets to close.

In the second variation there is no black pawn. It's a draw.

V-1

1.Qb8+ Kc2
2.Qh2+ Kb3
3.Qh8 Kc2
4.Qa1 Kb3
5.Kf6 Kc4
6.Kxe6
It's a win for white.

V-2

1.Qb8+ Ka1
2.Qh8+ Kb1
3.Qh1+ Kb2
4.Qg2+ Kb1
5.Qf1+ Kb2
6.Qe2+ Kb1
White can't make any progress.

Yancey_Ward

Editor

I am glad to see my mistake with the FEN didn't cause you problems, Alena. So, I asked for an explanation for why it has to be 1.Kg6- why does 1.Ke6 fail to win for white? Consider the two positions that exemplifies this issue: 7Q/8/4p1K1/8/8/8/p7/1k6 w - - 0 1 and 7Q/8/4K3/8/8/8/p7/1k6 w - - 0 1 In the first position, white has played correctly with 1.Kg6 and black has simply played king moves to capture the c and a pawns, put the king on b1 and pushed a2 in reply to h8(Q) as white pushed the h-pawn quickly. In the second position, white has erred with 1.Kxe6 and black has played Kc3-Kxc2-Kb2-Kxa2-Kb1-a2 as white has again queened the h-pawn. So why does white win the first position, but only draw the second. Note also that the first position drawn if the black e-pawn is missing! Can you explain that?

Alena

V-1

1.Kg6! e5
2.Kf5 Kc3
3.h4 Kxc2
4.h5 e4
5.Kxe4 Kb2
6.h6 Kxa2
7.h7 Kb1
8.h8=Q a2
9.Qh1+ Kb2
10.Qg2+ Kb3
11.Qg7
It's a winning position for white.

V-2

1.Kg6 Kc3
2.h4 Kd2
3.c4 Kc3
4.c5 Kb2
5.c6 Kxa2
6.c7 Kb2
7.c8=Q a2
8.Qh8+ Kb1
9.h5 a1=Q
10.Qxa1+ Kxa1
11.h6 Kb2
12.Kf6 Kc3
13.Kxe6
It's a winning position for white.

V-3

1.Kg6 e5
2.Kf5 Kc3
3.h4 Kb2
4.h5 Kxa2
5.h6 Kb1
6.h7 a2
7.h8=Q a1=Q
8.Qh1+ Kb2
9.Qxa1+ Kxa1
10.Kxe5 Kb2
11.c4
It's a winning position for white.

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