Thursday, August 30, 2007

Dos Hermanas, 2004

Dos Hermanas is a small city in Andalusia, Spain. It's named after two sisters who, after the conquest of Seville, discovered an image of Saint Anne.

In 2004, Dos Hermanas held a chess tournament. That brings us to our game of interest, between Emre Mecit and Juan Carlos Angel Acosta. We briefly discussed it yesterday, but today I want to master this endgame.

Mecit-Acosta, Dos Hermanas 2004

Which plan should White adopt?
    A. Block the a-pawn with his pawn and the f-pawn with his king
    B. Counterattack by capturing the a-pawn.

White fares very badly if he counterattacks. That's because White promotes in 11 moves, but Black promotes in only 7 moves! However, do check this plan in your games, because it works if the defender's pawn is far advanced.

So White's plan is to simply block the f-pawn by moving back and forth between e3, f3, g3, and f2. If you've studied King & Pawn vs King, you know the attacker won't be able to force the f-pawn's promotion.

Sciurus made the interesting observation that Black's king can wander just about anywhere he likes without changing the result. For example, 1... Kh5 2. Kf4 Kg6 3. Kf3 Kg5 4. Kg3 and Black can still win easily.

That actually makes sense. The White king is already ideally positioned to stop the f-pawn, and counter-attacking is doomed even with an extra tempo.

Which plan should Black adopt?
    A. Promote with the f-pawn.
    B. Use the f-pawn as a decoy and promote the a-pawn.

We already know the first plan fails, so Black must try to promote his a-pawn.

Black can wander around aimlessly as long as he likes, but as soon as he sacrifices his f-pawn, every tempo counts. He should choose his starting position for the upcoming race very carefully.

1...Kf6 2.Kf3 Ke5 3.Ke3 and Black will win the race. Not 2...Ke6? 3.Kf4!, when Black's only positioned to draw the race. This may seem tricky but it's not. Simply remember to shoulder your opponent whenever possible.

Even if you goof, there's no need to worry because the race hasn't started yet. Keep maneuvering your king until you obtain a favorable position.

And the race is on! Each player needs only six moves to reach the key squares (b2, c1), but Black moves first. Simple counting tells you Black will win!

But as you'll recall, Black didn't know Bahr's Rule, and played f4??. It happens to be the only move that draws. Why's that the case??

It's quite simple. After capturing the f-pawn, the defending king needs to reach the c1 square to draw. And f4 is closer to c1 than g4 is.

Hopefully now you have a deep understanding of this endgame, and you will be able to play it well whenever it comes up on the board.   :)

I reject the notion that you need Bahr's rule to play such positions accurately. However, Bahr's rule lets you evaluate and play such positions instantly and without error. And having that in your arsenal's a huge advantage.


Samuraipawn said...

I read to "...Andalusia, Spain." and started daydreaming. I love Andalusia and hope to move there...SOON! So I'm completely off topic and haven't read through your post yet. I'm a bad man, I know. ;)

transformation said...

a golden chess blog from A to Z, soup to nuts. bravo! just golden, pure, pure gold!

likesforests said...

Thanks. Although I could play this ending correctly before explaining it, lots of things begin to click as you look at it in detail and now more complex endings look less daunting.