Difficult King & Pawn Ending...

[Steve Maughan]

Here a position that's been discussed on Susan Polgar's blog (http://susanpolgar.blogspot.com/2008/01 ... stuff.html)

[d]8/8/7p/2p5/2P1K3/1kP1P3/8/8 w - -

It's a draw. But many of the top engines think that Kf5 wins for white. The engines that seem to have problems are Glaurung 2, Naum 2.2 and Rybka - Shredder and Hiarcs see that it's a draw. It's probably a position where the square of pawns rule breaks down. Anyway I thought it was of interest

[Uri Blass]

Here a position that's been discussed on Susan Polgar's blog (http://susanpolgar.blogspot.com/2008/01 ... stuff.html)

[d]8/8/7p/2p5/2P1K3/1kP1P3/8/8 w - -

It's a draw. But many of the top engines think that Kf5 wins for white. The engines that seem to have problems are Glaurung 2, Naum 2.2 and Rybka - Shredder and Hiarcs see that it's a draw. It's probably a position where the square of pawns rule breaks down. Anyway I thought it was of interest

The main problem here is that glaurung does not see that the following is a draw

[d]4Q3/8/8/8/7K/8/1kp5/8 w - - 0 9

Uri

[Jouni]

All engines I tested evaluate 0.00 including Rybka:

(Of course I have all IMPORTANT tbs)

Analysis by Rybka 2.3.2a 32-bit :

1.Kd3 h5
-+ (-1.53) Depth: 5 00:00:00
1.Kd5 h5
± (0.89) Depth: 5 00:00:00
1.Kd5 h5
-+ (-1.61) Depth: 6 00:00:00 0kN
1.Kd3 h5 2.e4
-+ (-1.53) Depth: 6 00:00:00 0kN
1.Kd3 h5 2.e4
± (0.97) Depth: 7 00:00:00 0kN
1.Kd3 h5 2.e4 h4
² (0.70) Depth: 7 00:00:00 0kN
1.Kd3 Ka4 2.e4 Ka5 3.Ke3
± (1.16) Depth: 8 00:00:00 0kN
1.Kd3 Ka4 2.e4 Ka5 3.Ke3 Kb6
± (0.90) Depth: 9 00:00:00 1kN
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5
+- (2.19) Depth: 9 00:00:00 1kN, tb=1
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5 4.Kg5
+- (2.17) Depth: 10 00:00:00 1kN, tb=2
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5 4.Kg5 Kc6
+- (2.35) Depth: 11 00:00:00 2kN, tb=4
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5 4.Kg5 Kc6 5.Kxh5 Kd6
+- (2.58) Depth: 12 00:00:00 2kN, tb=7
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 h4 5.Kg4 Kc6 6.Kxh4
+- (2.58) Depth: 13 00:00:00 3kN, tb=13
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 h4 5.Kg4 Kc6 6.Kxh4 Kd6
+- (2.58) Depth: 14 00:00:00 4kN, tb=20
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.08) Depth: 15 00:00:01 7kN, tb=29
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 15 00:00:01 9kN, tb=46
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 16 00:00:01 12kN, tb=63
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 17 00:00:01 16kN, tb=100
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 18 00:00:01 20kN, tb=149
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 19 00:00:01 26kN, tb=210
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.01) Depth: 19 00:00:01 52kN, tb=349
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.01) Depth: 20 00:00:01 71kN, tb=419
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.00) Depth: 21 00:00:02 95kN, tb=545
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.00) Depth: 22 00:00:02 124kN, tb=710

Jouni

[David Dahlem]

All engines I tested evaluate 0.00 including Rybka:

(Of course I have all IMPORTANT tbs)

Analysis by Rybka 2.3.2a 32-bit :

1.Kd3 h5
-+ (-1.53) Depth: 5 00:00:00
1.Kd5 h5
± (0.89) Depth: 5 00:00:00
1.Kd5 h5
-+ (-1.61) Depth: 6 00:00:00 0kN
1.Kd3 h5 2.e4
-+ (-1.53) Depth: 6 00:00:00 0kN
1.Kd3 h5 2.e4
± (0.97) Depth: 7 00:00:00 0kN
1.Kd3 h5 2.e4 h4
² (0.70) Depth: 7 00:00:00 0kN
1.Kd3 Ka4 2.e4 Ka5 3.Ke3
± (1.16) Depth: 8 00:00:00 0kN
1.Kd3 Ka4 2.e4 Ka5 3.Ke3 Kb6
± (0.90) Depth: 9 00:00:00 1kN
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5
+- (2.19) Depth: 9 00:00:00 1kN, tb=1
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5 4.Kg5
+- (2.17) Depth: 10 00:00:00 1kN, tb=2
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5 4.Kg5 Kc6
+- (2.35) Depth: 11 00:00:00 2kN, tb=4
1.Kf5 Kxc4 2.e4 Kb5 3.Kf6 h5 4.Kg5 Kc6 5.Kxh5 Kd6
+- (2.58) Depth: 12 00:00:00 2kN, tb=7
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 h4 5.Kg4 Kc6 6.Kxh4
+- (2.58) Depth: 13 00:00:00 3kN, tb=13
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 h4 5.Kg4 Kc6 6.Kxh4 Kd6
+- (2.58) Depth: 14 00:00:00 4kN, tb=20
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.08) Depth: 15 00:00:01 7kN, tb=29
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 15 00:00:01 9kN, tb=46
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 16 00:00:01 12kN, tb=63
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 17 00:00:01 16kN, tb=100
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 18 00:00:01 20kN, tb=149
1.Kf5 Kxc4 2.e4 h5 3.Kf4 Kb5 4.Kg5 Kc4 5.Kxh5 Kxc3 6.e5
= (0.00) Depth: 19 00:00:01 26kN, tb=210
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.01) Depth: 19 00:00:01 52kN, tb=349
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.01) Depth: 20 00:00:01 71kN, tb=419
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.00) Depth: 21 00:00:02 95kN, tb=545
1.Kf4 Kxc4 2.e4 Kb5 3.Kf5 Kc6 4.Ke6 h5 5.e5 h4 6.Kf7 h3 7.e6 h2
= (0.00) Depth: 22 00:00:02 124kN, tb=710

Jouni

Well, then, you're really not testing engines, you're testing the tbs.



Regards
Dave

[Jouni]

Yes finally a good position for TB benefit test

Jouni

[Alessandro Scotti]

Hi Uri,
I'm not a good player and trying to understand the position you posted. The usual "trick" of giving check with the queen until king moves in front of own pawn then using this tempo to bring the other king closer does not work because if king moves in the corner then it's stalemated when the queen captures the pawn... is this a correct summary?

[Uri Blass]

Hi Uri,
I'm not a good player and trying to understand the position you posted. The usual "trick" of giving check with the queen until king moves in front of own pawn then using this tempo to bring the other king closer does not work because if king moves in the corner then it's stalemated when the queen captures the pawn... is this a correct summary?

Yes

This is the reason that KQ vs KP when the pawn is in the 7th is often draw if the pawn is in the c file.

There is also a similiar case when the pawn is in the a file and it is also often drawn.

Uri

[tano-urayoan]

Generally bishop pawns in the 7th rank against queen could be drawn by the stalemate resource of moving the king to the corner square, so either c or f pawns. This is also available for rook pawns a, h. So beware of arriving at this endings. But if the side with the queen has the king in a specific zone and it is his turn to move there is a win.

I don't know how to insert a diagram with lines in it showing this winning zones.

[George Tsavdaris]

Generally bishop pawns in the 7th rank against queen could be drawn by the stalemate resource of moving the king to the corner square, so either c or f pawns. This is also available for rook pawns a, h. So beware of arriving at this endings. But if the side with the queen has the king in a specific zone and it is his turn to move there is a win.

I don't know how to insert a diagram with lines in it showing this winning zones.

This will probably help:
http://www.chesscafe.com/text/mueller22.pdf