Saturday, March 1, 2014

Rook vs 4th rank pawn + Rook: Part 1

I guess I've given y'all enough time to look through our previous challenge. Now let's look at the position again:

White to move: Can he win?

And most of ye got it correct: White can't win here, because the pawn is too far back and Black's king is close enough to keep it in check.

As a general rule of thumb, the stronger side wins if the weaker king is cut off by two files or more from the pawn. If the weaker side's king is closer, it is often easier to force a draw; however, this is also determined by the position of his king, and whether he is on the Long or Short side of the board (I hope you remember what these terms mean; otherwise go back to our previous topic!). If he can safely step in front of the pawn or gain the opposition after trading rooks, he can easily save his half-point.

While these guidelines holds true for central and bishop pawns, knight and rook pawns are exceptions; we will talk about that in a follow-up article. For now let's focus on central pawns.

As a reminder, this article will utilize most of the terms and knowledge that we have gained in the previous topic (5th rank pawn + rook endgames), so do make sure you are familiar with the content covered earlier on before we proceed: http://nushsblackknights.blogspot.sg/2014/02/rook-5th-rank-pawn-vs-rook.html


Central pawn, 1 file away, king on 6th rank

We return to our first position:

Draw regardless of who to move

The position here is a draw because of the following:

  • White's pawn is on the 4th rank, which gives Black's rook sufficient checking distance from the last rank (remember that when the pawn was on the 5th rank, White's king was too close to the last rank for Black to check safely from there. Always keep in mind that your rook must be as far away from the enemy king as possible when checking!)
  • The Black king's ideal position on c6 allows him to try some tricks which help to tie down White's pieces into defending each other. The variations here are quite tricky, so we shall go through in detail.



1. Kf4

Stepping out to support the advance of the pawn. If 1. Rc1+ Kd6 Black's king gets in front of the pawn

A trickier try is 1. e5 but Black can simply cut off the king with 1... Ra4 (1... Re8?? 2. Ke4 and White has a winning 5th rank pawn position, where Black's king is cut off by a file on the long side of the board) 2. e6 (2. Rd6+ Kc7 and Black's king gets in front of the pawn)

Now White threatens to win with e7 followed by Rd8, but Black stops this with a timely 2... Kc7! 3. e7 Ra8 with a draw. Note that if the king were on c5 rather than c6, this 2... Kc7 maneuver will not work; we will explore that later.

1... Rf8+

Notice how in our previous topic, the last-rank defense failed because the Black rook had insufficient checking distance. But here, it works because the rook is too far away to be stopped.

Also note that if Black tries 1... Rh8 threatening 2... Rh4+, it will fail because his rook is on the short side of the board with insufficient checking distance. Fortunately for him, he does not have to resort to this!

2. Kg5

Or 2. Ke5 Re8+ 3. Kf5 Rf8+ 4. Ke6 Re8+ with no victory in sight.

2... Re8

And not 2... Rg8+?? where White can get close to Black's rook with 3. Kf6 Rf8+ 4. Ke7 1-0

3. Kf5 Rf8+
4. Kg6 Re8
5. Rd4 (D)

Things are getting tricky

White tries something new, since 5. Kf5 Rf8+ gives no progress. This is the part where things get tricky for Black, so hold on tight!

5... Kc5!

Now both White's rook and pawn are attacked so he cannot advance the pawn. Notice that if the Black king were on c7 rather than c6, things might turn out differently; we will look at this later.

But Black's troubles aren't over yet: White still retains many threats to evade the rook checks and advance the pawn, so caution is required.

6. Rd5+

Of course 6. Rd1 Rxe4 will be foolish for White.

6... Kc6
7. Kf5 Rf8+
8. Ke5

The other variation is 8. Kg4, where Black draws by luring the White rook off the d-file so as to let his king step in front of the pawn. However, careful play is important as it is easy to botch up the position: 8... Re8 9. Kf4 Rf8+ 10. Rf5 Ra8. White's last move sheltered his king from the checks, but leaft the d-file open for Black's king to pass through. Now Black will not want to play 10... Rxf5+?? because after 11. exf5 he loses the opposition and the game. Rather, he gets his rook out of the way first. before marching his king in front of the pawn.

11. Rf7 (11. e5 Kd7 and Black is on his way to creating a Philidor Position) 11... Kd6 (D)

Position after 11... Kd6

12. Kf5 Ra5+ 13. Kf6 Re5 14. Rd7+ Kxd7 15. Kxe5 Ke7 and Black draws since he has the opposition.

Returning to our main line, things get easier after 8. Ke5:

8... Re8+
9. Kd4 Re7!

You'll see the point of this weird looking move later on!

10. e5

Or 10. Rc5+ Kd6 stepping in front of the pawn.

10... Rd7!

So that was the purpose of 9... Re7; by relocating to the 7th rank, Black can force a trade of rooks that allows his king to step in front of the enemy pawn!

11. Rxd7 Kxd7
12. Kd5 Ke7

1/2-1/2

With a hopelessly drawn king + pawn vs king position.


Central pawn, 1 file away, king on 5th rank

Remember how I said earlier that Black might run into some problems if his king were on c5 rather than c6? Let's take a look!

White to move wins since Black is on the long side of the board

In such a position, the outcome is determined by whether the weaker side's king is on the Long or Short side of the board.

If it were Black to move he will simply draw by 1... Kd6 returning to our first position. But if it were White to move, he wins because Black's king is stuck on the long side of the board.



1. e5 Ra4

Attempting to cut off the king as usual, but now White can exploit the Black king's unfortunate position:

2. Rd8! Rh4
3. Kf3

Exploiting the Short side of the board: Black cannot shuffle his rook safely, and if he goes over to the long side the Black king gets into the way!

3... Kc6

Notice how if the king were initially on c6 rather than c5 he could simply play a timely 3... Kc7 kicking the White rook away. But now the pawn has time to rush over and protect his fellow rook:

4. e6 Kc7

Black would love to play 4... Re4 and put his rook behind the enemy pawn, but the presence of the White king on the fatally short side of the board prevents him from doing so. Meanwhile, 4... Rh6 is answered with 5. e7

5. e7
1-0

There is no stopping the pawn from promoting.

So how does Black draw if his king were cut off on the short side of the board instead? In the interest of time I won't go through this; you can try it as a personal challenge (:


Central pawn, 1 file away, king on 7th rank

Similarly, if the Black king was initially on c7 instead of c6, Black's situation becomes problematic because he does not have a Kc5 defensive idea to counter Rd4.

White to move wins, Black to move draws

If it were Black to move he can draw in two different ways: 1... Kc6 (returning to our first position) or a faster method by 1... Rd8 (what's the best way to get rid of a sniper? Well, snipe him back!)

Mother of God...

2. Rxd8 Kxd8 3. Kf4 Ke8 (NOT 3... Ke7?? 4. Ke5 losing the opposition) and Black draws after taking the opposition.

If it were White to move, however, then he wins with the Rd4 trick because Black can no longer use the Kc5 defense:



But what happens if the Black king were on the short side of the board? Can he still draw? Once again, I will leave this to you as a personal challenge!

...

Ok, I admit that even I myself got quite confused when typing this. It seems there are so many factors to take into consideration when the pawn is on the 4th rank. So let us try to tidy up what we've learned in this article to make things easier.

For a rook + pawn vs rook position where the pawn is  a central/bishop pawn on the 4th rank, and the weaker side's king is cut off by one file, the following general rules will help determine the outcome of the game:

  • If the weaker side's king is separated from the pawn by one rank (i.e. on the 6th rank), then he can force a draw regardless of whether he is on the long or short side of the board!
  • If the weaker side's king is on the 5th, 7th or 8th rank, however, then the side of the board (and who to move) determines the outcome of the game. As a rule of thumb, the weaker side should strive to place his king on the short side of the board, so that his rook has sufficient checking distance on the long side.
  • As usual, the game often steers towards a draw if the weaker side can get his king in front of the pawn.

In Part 2, we will look at how the stronger side can force a win if the weaker side's king is cut off by two files or more from the pawn.

Links:
Pawn on the 5th rank: http://nushsblackknights.blogspot.sg/2014/02/rook-5th-rank-pawn-vs-rook.html

Source:
http://imgur.com/gallery/BNw77
"Silman's Complete Endgame Course" by Jeremy Silman

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