Monday, 9 August 2010

From Philador to Lucena

I'll start with a sort, shameful confession. At the 2008 Chess Olympiad I reached a rook and pawn ending where I had the Lucena position. This is a book win for the player with the extra pawn (ie me). However, despite teaching it plenty of times over the years to juniors, I had a brain freeze, and failed to convert.
So I kind of felt sorry for one of the junior players at my local club last week. He was actually defending the position (ie he had R v R+P) but had managed to reach the Philador position (See diagram for example). However, having done all the hard work, he played the fateful check, and suddenly it went from the Philador, which is drawn, to the Lucena, which is lost.
In the diagrammed position (which btw wasn't the exact position from the game), White plays 1.Kf6! If instead 1.Ke6 then 1. ... Ra6+ 2.Kf5 Rb6! If White pushes 3.e6 then 3. ... Rb1! draws by checking from behind. Now the key move for Black is 1. ... Re1! If instead 1. ... Rf1+? then 2.Ke6 Kd8* 3.Rh8+ Kc7 4.Kf7 and White will achieve the Lucena position (which is what happened in the game). 2.Ke6 Kf8! (The 'short side' defence) 3.Rh8+ Kg7 4.Re8 Ra1 and Black can hold the draw by a combination of checks and bringing the king back towards the pawn.

*Edit: 1. ... Rf1+ doesn't lose, if Black plays 2. ... Kf8. So attach ?? to 2. ... Kd8. See comments to this post for source of correction.


Mark Weeks said...

The tablebase doesn't agree with you. The sequence 1...Rf1+ 2.Ke6 Kf8 (instead of 2...Kd8?) also holds the draw. - Mark

Shaun Press said...

D'oh! I'm relying on analysis from Soltis, but I'm sure your correct.