## Wednesday, November 27, 2013

### A simple case of zugzwang: The trebuchet

In highly complex endgames it is always useful to steer the game towards basic endgame positions that you know-- opposite-colour bishops, Lucena and Philidor's positions, King+Pawn vs King, just to name a few-- so that the seemingly difficult position becomes a simple problem.

So let's take a look at the following basic position:

A quick look should be enough to tell one thing-- whoever to move is in zugzwang. Whichever king moves first will be unable to defend his own pawn, thus allowing the enemy king to gain both the pawn and the Opposition. So for example if it is Black's turn to move, then after 1... Kg5 2. Kxe5 Kg6 3. Ke6 Kg7 4. e5 White wins since his king is in front of the pawn and Black cannot gain the opposition.

In fact, this is such a well-known basic endgame position that it has a name: The Trebuchet

 You want some of these?

The Trebuchet looks so damn easy to understand, I know most of us will wave it off as trivial and move on to concentrate on other important topics. But just to keep in mind, having a firm understanding of such simple positions like these can be helpful even when it comes to a complex situation like this:

 White to move: Who's winning here?

Without having any prior knowledge many amateurs would probably panic at this position, but now with a basic understanding of the Trebuchet one should be able to play it out easily: The side who wins is the one who can make first diagonal contact with the central pawns and thus attain a winning Trebuchet position.

So Black, with his king closer to the pawns, should not find it difficult to secure the win here:

1. Kxb6 Kxg3 2. Kc5 Kf3!

Don't be a dunce and play 2... Kf4?? where after 3. Kd5! Black is now on the losing side of the Trebuchet

3. Kd5 Kf4

And we have the same position as in our first diagram, where White has been forced into zugzwang

And thus we can clearly see that in positions where a Trebuchet is imminent, the winning side is the one who can get his king to make first diagonal contact with the Trebuchet pawns. With this in mind, one will be sound enough to avoid blunders like 2... Kf4?? in our previous example.

And so do remember to add this concept to your arsenal of endgame knowledge. Like the Lucena and Philidor's Positions in rook endgames, it is a useful one to remember when it comes to handling complex pawn endgames.

Sources:
http://www.ucantalk2me.com/cooltalk/trebuchets/science-behind-trebuchet-attack.html
"Silman's Complete Endgame Course" by Jeremy Silman