Wednesday, June 10, 2015

Practical Rook Endgames 03: Spread Offense or Screen Pass FTW

I used to watch football, but now I hardly do partly out of protest since Traumatic Brain Injury came to the forefront. This football-themed chess set seems like it would be difficult to play with as there seems to be little differentiation between tight ends and wide receivers. I assume that the running backs would be used as bishops because they are taller.

In the previous Practical Rook Endgames, I showed how a recent game ended with my opponent helping me to get a Lucena type ending. But he didn't need to be so cooperative. Let's start with the beginning position of that post.

After 61...Kh4, White to give Black headaches

In the game, my opponent played 62.Rg1-g8 which made my job easy. He could have tried to be annoying as possible by crossing up my ill-conceived plan. My plan was to advance my king down to g2 or f2 and then escort the pawn safely to f4. But the rook can force my rook to play Rd6-d5 which creates a narrow path to victory in the tablebase. 62.Rf1

Headache begins after 62.Rf1

If I want to keep my rook free, I have to protect with my king. 62...Kg4. Then 63.Rg1+ Kh3 64.Rf1 Kg4 65.Rg1+ shows the folly of the king attack plan.

Because the rook has enough checking distance from the pawn, Black has to resort to using the rook to defend the pawn. What if Black's rook gets behind the passer? Instead of 64...Kg4, try 64...Rf6?.

64...Rf6? Rooks don't always belong behind passers

The Shredder tablebase evaluations collapse to draws in all variations with best play starting with 65.Kd4! Kg4 66.Ke5 (gaining one crucial tempo) 66...Rf8 67.Rg1+ Kf3 preventing Ke5-f4 68.Rf1+ Kg4 69.Rg1+ drawn.

In many of these variations, rooks have to trade file cutoffs with lateral moves to ensure the pawn gets to the 5th without allowing a blockade. So instead of 64...Rf6?, 64...Rd5! preserves the win.

64...Rd5! Prelude to Motion

65.Kc4 Ra5!

64...Ra5! The Spread Offense

In my football analogy, the pawn is a slow fullback carrying the ball. The Black Rook is a wide receiver who just ran to the right sideline to spread the defense. The Black King is a lead blocker for the fullback, perhaps a tight end trying to stay between his fullback and the White Rook which is the defending linebacker. White can chase the wide receiver with his king (strong safety?) 66.Kb4 Re5 67.Kc4 Kg3! 68.Kd4 Ra5!.

68...Ra5! Black is ready to advance the ball

The ending takes a while to morph into a Lucena, but the presence of the lead blocking tight end Black King makes sure Philidor doesn't come up. 69.Rg1+ Kf2 70.Rg5 Ra4+ 71.Kd3 Ra3+ 72.Kd2 f4 73.Rf5 f3 74.Rf8 Ra7

74...Ra7 Lucena about to appear

Rd7 or even Re7 will ensure Lucena again.

Let's go back to the position at the beginning.

After 61...Kh4, White to give Black headaches

Black decides that fighting the White Rook with the King and Pawn are the way to go and risking a repetition is okay. 62.Rf1 Kg5 63.Rg1+ Kf6 64.Rf1 Now in this football analogy, the Black Rook is going to be the quarterback, the Black King is going to be a pulling lineman, and the pawn is going to be a fullback who receives a screen pass. 64...Rd8 The quarterback takes the snap out of the shotgun. 65.Kc4 Kg5

65...Kg5 The Lineman Pulls for a Screen Pass

Now we'll try the same harassment strategy for White's rook 66.Rg1+ Kh4 67.Rf1 Kg4 68.Rg1+ Kh3 69.Rf1 Rf8

69...Rf8 The Quarterback Sidesteps the Rush and Throws the Screen Pass

Notice that there are only two differences between the third diagram of this post and this diagram: The White King is at c4 instead of c3 and the Black Rook is at f8 instead of f6. Whereas Rf6 led to a draw in all variations, here, Rf8 is winning. White doesn't have the crucial tempo gained from Ke5 attacking a rook at f6. The strong safety runs back to try to bust up the screen play while the pulling lineman pushes the linebacker around. 70.Kd4 Kg2 71.Rf4 Kg3 72.Rf1 f4 73.Rg1+ Kf2 74.Ra1 Re8. To add insult at the end of the play, the quarterback lays a killer block on the strong safety and Lucena is on.

Screen Pass Successful - Lucena Achieved

In the next post, we'll see how White missed an obscure theoretical draw and also how Black can totally violate the Rule of Five and win.

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