Monday, April 6, 2009

Instructive Rook Ending

First: a shout out to chunkyrook. His endgame posts helped get my gumption level up to posting some endgame analysis of my own. I also rather liked this example of seizing a file...a fairly simple idea, yet one that was new to me.

Sometimes I get a basic ending that I thought I knew reasonably well , and then after analyzing it I realize how much of endgame play is still mysterious. I had two such instances recently where the analysis was instructive. Here is the first, which should have a dead-drawn R+P vs. R endgame. I was black:

I had just captured on c5. The defending king is able to get in front of the pawn, which should be an easy draw. A rule of thumb in 1-pawn rook endgames is the "Rule of 5": if the number of the rank of the pawn, plus then number of files the defender's king is cut off, is greater than 5 then the side with the pawn wins. There's exceptions but it beats assessing a position by coin toss. With a pawn on the third rank (counting from Black's side) the defending king would have to be cut off by 3 files to be winning according to the Rule of 5. Here, you don't even need to invoke the rule: the king isn't cut off at all and is free to get in front of the pawn, so this should be a cakewalk for White. However, after 76. Kd3 Rc1 77. Ra4 Kb5 78. Rh4 c5 79. Kd2 Rg1 80. Kc2 Rg3 81. Rf4 c4 82. Rh4 Kb4 83. Rh8 (threatens a series of checks from the rear, a theme of the Philidor position we are arriving at) Rg2+ 84. Kc1 Kc3 85.Rh3+ Kb4:

This should be a dead drawn Philidor position. For those unfamiliar with this ending, the Philidor position is one of the standard defensive techniques. All White has to do now is keep his rook on the third rank (e.g. 86.Rf3), which prevents White from getting their king ahead of the pawn. If Black delivers checks from the side, the White king just bounces between c1 and c2. If Black tries to make progress by advancing the pawn, White can play the rook to the 8th rank and deliver endless checks from the rear. If this drawing method isn't familiar to you, it's one of the first rook endgames you'll want to study.

However, my opponent played 86. Rh4?-+, probably thinking this prevented advancement of the pawn because of the pin. However, 86... Kb3 is now a win for White--but only barely! The king can use the pawn as shelter against a check on the 3rd rank. After 87. Rh8, a critical position has been reached:

87... Ra2?= If the pawn were on c3, and White was passively defending with a rook on the first rank, ...Ra2 would be involved in the winning line. This method of playing against passive defense is another basic rook endgame, but that's irrelevant to this position. Short on time, and with a 12-second increment on the clock, I was going with my gut at this point.

There is only one winning move here: 87... Rg1+! and it turns out that after 88. Kd2 c3+ white wins:

For example 89. Kd3 Rd1+ (89...Rg3+ also wins) 90. Ke3 c2 91. Rb8+ Ka4 92. Ra8+ Kb5 93. Rb8+ Ka6 94. Ra8+ Kb7.

I have not seen this winning method in any of my endgame manuals, yet it seems important. If anyone has seen this covered before, can you let me know where?

The game continued 88. Rb8+ Kc3

89. Kb1! Well played. This ending appears similar to one covered in Dvoretsky's Endgame Manual as well as (if memory serves) Soltis' Grandmaster Secrets: Endings. Dvoretsky mentions Philidor's "second defensive method": if the rook can't occupy the cutoff rank, it should place itself behind the pawn. The king goes to the "short side" of the pawn (i.e. the side with less space between the pawn and the edge of the this case the left side). Because the defending king is on the "short side", the attacking king is on the "long side" and if it tries to squeak out the long side it can be subjected to checks from the side.

89...Rh2 90. Rd8 This also draws, but 90. Rc8 is the thematic "attack the pawn from the rear" second defensive method. After 90.Rd8, White needs to be careful. 90... Rh1+ 91. Ka2 Kc2 (if the defending rook were on c8, this move would just lose the pawn to Rxc4)....

92. Rd7?-+

Now we see why the "short side" defence is an important resource. Because White's rook didn't stay behind the pawn, it is able to advance. Now the only way to draw is from side checks, e.g. 92. Rg8! (or 92.Rf8!) 92...c3 93. Rg2+ (93.Rg3 also draws) and if 93...Kc1 94. Kb3.

After 92.Rd7? there are still a few tricks involved in winning the endgame. 92... Rh5 wins, but the endgame tablebases reveal this shorter and sneakier winning line: 92... Rh8! 93. Ka3 c3 94. Rc7 Ra8+ 95. Kb4 Kb2!!

with the point 96. Rxc3 Rb8+ 97. Kc4 Rc8+ wins the rook. This appears to be an important resource. Several of the lines I analyzed in this endgame resulted in this position.

93. Ka3 Rc5?=

This allows checking from the side. It turns out the only winning move is 93... Rh3+! 94. Ka2 (94. Kb4 c3 95. Rc7 Kb2 is the sneaky win mentioned above) 94... Rh8 and wins.

94. Kb4?-+ (Many moves draw, but 94. Rh7 with the idea of checking from the side appears simplest, e.g. 94...c3 95. Rh2+)

94... Rc8! Now rook behind the pawn wins. Black can advance the pawn and use it as a shield from side checks. 95. Rd4 c3 96. Rh4 Kc1 (96... Kb2 is shorter) 97. Rh1+ Kb2 98. Rg1 c2 99. Rg2 Kb1 100. Kb3 c1=Q 0-1

Even the simplest rook endgames are difficult to play perfectly. Familiarity with the basic positions (e.g. Lucena/Philidor) and concepts (checking distance; Rule of 5; playing the king to the short side; defending via repeated checks from rear/side/front) help guide you in the right direction (86.Rf6; 89.Kb1!; 94.Rh7 etc.). However, sometimes there's no substitute for calculation (87.Rg1!).


Aziridine said...

Fantastic stuff!

Chunky Rook said...

Thanks for the shout out and the interesting post. Having barely scratched the surface, I stand amazed by the subtlety of rook endings.

Will said...

GM ram has a few rook ending positions that you are asked to analyse deeply, 87 Rg1+ was the first move I looked at which I can only attribute to analysing one or two of the positions. The method of winning is familiar but I can't think where I have seen it.

Anonymous said...

amazing that your opponent played Rh4??, but it's a good instructive ending. Here are some other positions, such as the back rank defense and vancura that are worth knowing.