Tuesday, May 27, 2008

Another Example of Engame Transitions

This post is in part to let people know I'm alive, and in part to whet my blogging appetite. The end of the semester has been a busy one. I have a couple of book reviews that I've been dragging my heels on but should post shortly.

This is from an online blitz game (2+12 time control). Evaluate 1.Rb5.

I was Black and had been suffering all game. Finally my opponent slipped with 1.Rb5?? I had been hoping for this, but didn't think my opponent, who had played credibly to this point, would fall for it. Even if my opponent had been in time trouble (which he wasn't), 12 seconds is enough time for someone our level to follow the most forcing line and see that this move is bad.

1...Rxb5! is forced, otherwise the h-pawn drops and the connected passed pawns win. After 2.axb5, black steps into the square of the passed pawn, e.g. 2...Ke7:

Now Black will have a protected passed pawn, which takes care of itself while Black's king gobbles the isolated passed b-pawns: 3.Kg5 g6! 4.f4 Kd6 5.f5 Kc5 6.fxg6 fxg6 0-1.

It was only necessary to follow the most forcing moves 4 ply ahead (up to 2...Ke7) to see that White's chosen move loses--assuming a basic knowledge of pawn endgames. Knowing the rule of the square means, for example, that you don't have to calculate ahead another 6 ply to see whether White can promote a pawn safely. It also means you don't need to calculate much to convince yourself that Black's kingside pawns will be safe. After g7-g6, Black has a protected passed pawn. If White tries to capture the base of the pawn chain, the king will be out of the square of the leading pawn, which will go on to queen. If anything in this last paragraph isn't clear to you ("What's 'the square'?") I strongly recommend picking up a basic endgame book (Silman, Pandolfini, or Alburt for example) and getting started.

One possible explanation for my opponent's move is just a silly oversight (I know those all to well), perhaps thinking Black's king wouldn't be able to get into the square of the pawn. It's also possible that they just haven't studied endgames much, and that certain themes such as the square of the pawn or the strength of a protected passer were not yet second-nature. My reason for choosing this position was to demonstrate once again the importance of endgame study: it's not just so that you know the technique required to win a certain endgame, but also so that you can spot transitions to winning endgames...or, to avoid transitions to losing endgames.

By the way, the theme of analyzing the most forcing sequence of moves is foreshadowing for my next mini-book review.