Saturday, December 14, 2013

Revising Basic Rook endgames: Part 2

In our previous section we revised two basic positions (well I hope they're still fresh in your mind!) and saw the winning/drawing strategy behind them. Today let us take a look at other basic functions which rooks have in the endgame: 1. Cutting off enemy units from the main action and 2. Escorting or preventing the promotion of passed pawns.

Cutting off ranks/files from the enemy

In our revision of the Lucena and Philidor Positions we saw how the rook was able to fence off an entire row of squares to prevent the opposing king or pawn from stepping across it.

Philidor Position: Black's rook fences off the entire 6th rank from the White king

And yes-- it is indeed the long range capabilities of the rook that enables it to lay suppressing fire along a rank or file to cut it off from enemy infantry. As we are to see this is an extremely useful tool be it in attack or in defense-- for when the enemy is approaching, CALL IN THE BARRAGE!!!

Will there still be Huns left for us to fight, sir?

Alright let us see how this actually works. Look at the following position:

White to play and win

Over here Black is down in material, but he knows that if he can trade off his pawn for the enemy rook the game will be a quick draw. So he will try to use his king to escort the pawn to promotion and lure the rook in for an exchange. White, obviously, does not want the pawn to promote, so he must find a way to win the Black pawn without having to sac his rook. Which seems to be quite of a problem for him, since his king is too far away to participate in the action...?

But one thing ensures victory for White. The Black king is separated from the pawn by a file, so White simply severs their connections with the simple:

1. Rh5!

And not 1. Rh4? or 1. Rh6+? where after 1... Kb5! Black's king makes contact with the pawn, and White can no longer hope to win the pawn without having to lose his rook.

And with the 5th rank fenced off Black cannot hope to escort the pawn safely down the board, for 1... c3 is met by 2. Rh3 winning the pawn, while any king move is met by 2. Kf7 and the White king will eventually move in to take out the pawn.

(It is interesting to note that if we shifted the Black king and pawn down one square, the strategy will not work because after 1. Rh6 c2! the pawn is on the verge of promotion and White cannot hope to play 2. Rh2?? and win the pawn. But nevertheless in this example we can see the power of using rooks to deny the opponents access to entire ranks/files)


Want another example? Here goes:

White to move

Black is a pawn down, but he can hope to save half a point if he is able to get his king in front of the pawn and create a Philidor Position. IF.

And his dreams are busted the moment White plays 1. Rf1! cutting the Black king off and preventing him from ever reaching the pawn. After 1... Rf7 2. Rxf7 the resulting king-pawn endgame is a win for White.


The idea of using rooks to cut off ranks/files does not always have to be a tool for the stronger side; in our next example, the weaker side uses the same concept to force a draw.

Black to play and draw

White wants to play Kc5 and win the d5 pawn, after which his two-pawn advantage should be enough to ensure victory. But Black manages to find a good defending move by denying White access to the c-file:

1... Rc8!

And by simply shuffling his rook along the c-file White cannot find any way to reach the mass of pawns in the centre; for example after 2. Kb5 Black continues with 2... Rf2 hitting the f2 pawn.

As such we can see how the long-range capabilities of the rook enable it to fence off whole ranks/files from the opponent, which comes as a useful endgame tool be it in offense or defense.


The escorting of passed pawns

A infantry battalion assaulting a fortified base usually cannot complete the mission on its own; The soldiers have rely on airstrikes or artillery support to clear out any major threats, before moving in to capture the base.  Similarly a passed pawn advancing across the board cannot reach the other side all by itself. It needs close support from friendly pieces, which help to remove any obstacles in its path to promotion. Without this support the pawn cannot make inroads into the enemy camp, and instead becomes a vulnerable target of attack.

And in rook endgames, the two pieces tasked with escorting passed pawns-- and similarly the enemy pieces which stand in its way-- are the king and the rook. In such positions, Tarrach's old quote about rooks and passed pawns come to mind:

"Always put the rook behind the pawn.... Except when it is incorrect to do so."
-- Siegbert Tarrasch


The logic behind this is quite simple-- the infantry should be the one in front doing the chiong sua while the artillery supports it from behind, not the other way round. While there are some exceptions to this rule (see http://en.wikipedia.org/wiki/Tarrasch_rule for some exceptions) we're gunning for concepts, not brute force memorization over here. So for now let us accept that Tarrach's rule holds true for the majority of rook + passed pawn endgames.

White to move

Tarrasch's rule holds quite clear in this position: White's pawn is well supported from the rook behind, and the Black rook is helplessly tied down to the defense of the h8 square. White wins by walking his king over to g7 (he has the opposition since it is his turn to move) and chasing away the Black rook.

On the other hand, if we switched the positions of the rooks:

Draw no matter who to move

Once again we see the power of Tarrach's rule: Now White cannot move his rook for fear of 1... Rxh7 with a draw! So all Black has to do is to shuffle his rook along the h-file (and not falling for 1... Kc7?? 2. Ra8! where after 2... Rxh7 3. Ra7+ Black loses) and White can never make progress.

In actual rook endgames the methods for winning/drawing is often not as simple as what I've shown above (we'll go through some of the challenges faced in later articles), but the first step is always the same-- in most cases, when escorting or preventing the promotion of far-advanced passed pawns  you should try to put your rook behind the passed pawn regardless of which side it is on. This is an important thing to note when it comes to rooks + passed pawn endgames.


So in case you've become lost after reading all those text above, I've summarized what we've revised today into two simple points:

  1. The long-range abilities of the rook enable it to cut off whole ranks/files, thus denying opposing kings/pawns access to them. This can become an extremely useful tool in both offensive and defensive tactics
  2. When escorting or preventing the promotion of passed pawns that have advanced far up the board, Tarrach's rule (to put your rook behind the passed pawn) holds true for most cases.

Similar to Part 1, do take your time and revise these basic concepts, for they will serve as valuable guiding posts when it comes to learning more complex endgame positions in the future.

Links:
Part 1: http://nushsblackknights.blogspot.sg/2013/12/revising-basic-rook-endgames-part-1.html

Sources
"Silman's Complete Endgame Course" by Jeremy Silman
http://vuel-iqbal.blogspot.sg/2012/05/operation-bagration-is-go.html
http://en.wikipedia.org/wiki/Tarrasch_rule

No comments:

Post a Comment