Friday, November 23, 2007

Forced Patience

With a handful of pieces still on the board, having your king in front of your pawns is usually a bad idea; venture too far into enemy territory, and your king will be a rabbit on the run.

However, the hunter still has to find the right moves to make the most out of an exposed king. In calculating a position such as the one below, we're prone to think along forced lines: "I check, he has to go there, then I check here, he goes there, I check here, he goes there, etc. etc.". The challenge is to find the one move that does not immediately force things, but rather paves the way for a forced win. Look at the board. White to move -- do you see the rabbit trap?

Bd5 was my original plan (the rook at a8 is trapped). Then I started pondering f4+, luring the king into a mating net. I began calculating -- f4+, Kxe4, Re1+, Kf5, Bd3+, Kg4, ... at that point, I more or less convinced myself that after Kg4, there had to be a winning continuation (even though I didn't bother calculating things out).

What I should have considered in my calculation, however, is the one quiet move that seals the deal! After 1. f4+ Kxe4, White has the move 2. f5! -- the king cannot escape, and Black cannot bring in any defenders, either. 2. ... Bxf5 3. Re1#!

Lesson learned: in calculating forced variations, watch out for quiet moves as well.


Anonymous said...

1. Bd5 f5 - protecting the e-pawn, attacking the rook and threatening mate with 2. f4 (three purposes so surely this must be the key move!), Black's only escape is to move the f-pawn out of the way so his king can get to the f6-square.
2. f4+ Kf6
3. e5+ Kg6 - Instead of taking the rook, this creates two connected passed pawns with a check. I was looking at a mate at this point, but I couldn't fine any.
4. Bxa1 which is a very winning position.


Anonymous said...

I couldn't get it solved, (also because I lose the position in my non-trained head after three moves). The pawn sacrifice is nice, you don't expect a small pawn to be of any interest when you have two bishops and rooks there.

Well, I still would have won the game though. That's a consolation. =)