Wednesday, February 5, 2014

Passive rooks shall stay passive

So not long ago I issued the 2nd LNY challenge, and I present it here again in its full glory:

White to move: Can he win?

The answer, as most of ye have pointed out, is NO. The unfortunate position of White's rook, Black's active rook, and the fact that White's king is away on a holiday is enough to save half a point for Black.

But here's the interesting bit: Black draws not because he can keep his rook behind White's pawn (as some of you have pointed out), in fact if he follows the same method the game will end in a win for White.

Rather, Black draws because he can set up a Vancura Position, which is a draw for the weaker side. You didn't think I was going to let you get away reading through and forgetting all our previous content, yeah?

So first of all, let's see why Black cannot win if he lets his rook stay behind the pawn:


The main reason why this position is different from the one we saw in our previous article (with the pawn on h7), is because the White king now has a shelter on h7 which will prove useful to him. White wins by slowly marching his king towards the g-file, making sure that he stays on the first and second ranks to make sure Black doesn't seize control of that file. Once he has reached the g-file, he can then then march up the file to make contact with his pawn, before exploiting the shelter on h7 to escape from the rook check (which would not have worked had the pawn been on h7) and free his rook from its passive slumber.

1. Kc2 Rh3
2. Kd2 Rh2+
3. Ke1 Rh1+
4. Kf2 Rh5
5. Kg3 Rh1

Stage 1 is complete: White's king has reached the g-file. Now he slowly walks towards his pawn

6. Kg4 Rg1+
7. Kf5 Rh1
8. Kg6 Rg1+
9. Kh7

Stage 2 is complete: White tucks his king away safely on the h7 square, and his rook prepares to step out. The rest of the game should be easy by now:

9... Rc1

Desperate counterplay since staying on the g/h files allows Rg8 followed by Rg6, allowing White's king to step aside and let the pawn advance.

10. Rf8 Rc6

10... Rc7+ 11. Kg8 Rc1 (preparing 12... Rg1+) 12. Rf7+! also loses quickly for Black

11. Rf7+ Kb6
12. Kg7 (D)
1-0

A free road for the pawn

So now we see why letting the rook stick behind the pawn is no longer effective for Black in this case. But he still has one more weapon hidden under his sleeve, which we have all looked at not long ago: The Vancura Position.

Returning to the original position, we can now see that Black can easily force a draw by setting up a Vancura Position:

Black finds the correct method to draw

1. Kc2 Re1!

Or 1... Rf1/Rg1. The purpose is the same: To leap to the 6th rank where Black can tie down the pawn and deny the White king passage to the h7 square.

2. Kd2 Re6

Of course if 2. a7 Black simply draws by returning to the h-file with 2... Rh1

3. Kd3 Rc6 (D)
1/2-1/2

Looks familiar?

With a Vancura Position, and a draw. And if you've forgotten how to handle this position, well... here goes: http://nushsblackknights.blogspot.sg/2014/01/the-vancura-position.html

...

So that was easy... but some of you might be wondering, does this still apply if the pawn is not a rook pawn?

White to move: What happens now?

This time Black cannot hope to draw by setting up a Vancura Position, because the White king can seek safety on h6 (see the KnightVision viewer below for easier visualization):

1. Kc2

Of course 1. g7? Rg2+ is a draw

1... Re1
2. Kd2 Re6
3. Kd3 Rc6

Attempting to stall White's king march by shuffling along the e-file will only free the White rook from its position: 3... Re1 4. Rf8

4. Ke4 Rc4+
5. Kf5 Rc5+
6. Kg4 Rc6 
7. Kh5 Rc5+
8. Kh6
1-0

Hiding from the rook checks, and unleashing White's rook into the fray.

So is this a losing position for Black? The answer is NO; even though the Vancura Position does not work here, the pawn on g6 is closer to Black's king than the pawn on h6, so Black can (surprisingly) draw by moving his king towards the pawn!

1. Kc2 Kc7!
2. Kd2 Kd7

Marching slowly towards the prized target on g6, while keeping the rook behind the pawn; although this fails with a rook pawn, it surprisingly works for a non-rook pawn!

3. g7

If 3. Ke2 Black will proceed with Ke7 followed by Kf7, picking off the pawn

3... Ke7
4. Ra8

Played along the same lines as the tactical trap with the pawn on h7; but this time, White cannot hope to exploit the skewer because the enemy king is too close to the pawn.

5... Rxg7
5. Ra7+ Kf8
1/2-1/2


So we can take away three simple learning points from this article:

  1. In a position with a rook pawn on the 7th rank, the stronger side's rook in front of the pawn and the stronger side's king too far away to help, the weaker side draws by shuffling his rook behind the enemy pawn. However, care must be taken not to fall for any tactical traps!
  2. In a similar position but with the rook pawn on the 6th rank, the weaker side draws by setting up a Vancura Position.
  3. In a similar position but with a central pawn instead of a rook pawn, the weaker side cannot draw by setting up a Vancura Position; however, he can draw by rushing his king to the pawn in order to pick it off.

Of course, all these is thanks to the passive position of the stronger side's rook, and the active position of its weaker counterpart.

By now you should be quite familiar with most of the rook endgame basics, so absorbing these should not be much of a problem for y'all.

Links:
The Vancura Position: http://nushsblackknights.blogspot.sg/2014/01/the-vancura-position.html
Passive rook + Pawn on 7th rank (Part 1): http://nushsblackknights.blogspot.com/2014/02/2nd-lunar-new-year-challenge.html

Source:
"Silman's Complete Endgame Course" by Jeremy Silman

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