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Improve your calculation: Prophylactic thinking

Improve your calculation: Prophylactic thinking

linlaoda
Nov 2, 2015, 11:18 AM 10

Prophylaxis is a well known concept, but for those unfamiliar to it, it is the process of preventing your opponent's counterplay. Basically, this is where it is recommended to be a pain in the arse for your opponent.

 

Before we start, first try to solve the following puzzle for White to move. Spend up to 30 minutes.

 

 

 

 

 

 

 

 Before we discuss the solution, let's try again but this time adding prophylactic thinking to our arsenal. The process here is:

(1) What is my opponent's counterplay? If it is clearer, you can also think: What is my opponent trying to do? It may be useful here to pretend you are in your opponent's shoes when thinking about this.

(2) How do I prevent this?


Try to solve the puzzle again, before scrolling down for the solution.
Spend up to 1 hour.

**Solution below** 


At first glance, this position looks like a trivial win for White. White just plays 1. Bxe6 and the passed pawns will win immediately. After 1...Nf8? White is just a pawn up and will win soon.

But then we start to think about our opponent's counterplay. Clearly, our opponent is trying to draw - in this case we should be thinking about the theoretically drawn endgames here. A most famous theoretical draw has to do with the "wrong bishop." Have a look below:

 

If you are unfamiliar with this ending, the simple explanation is that White would prefer the bishop is of dark color in order to control the dark promotion square h8.


(Note: the ending is much more complicated when the Black king is not already in the corner, although when we are using prophylaxis, since we are thinking from our opponent's shoes it is useful to think about the idealistic situation for them.)

**Prior knowledge of this endgame would help greatly with this puzle - goes to show that we should invest time to learning the basic endings.**

Now, back to the puzzle. A logical first move for White is 1.Bxe6. (Why? This is the most principled line as it fits with White's strategic goals. See Test your Chess: Tactics and the Principled line for a more detailed discussion) 

Then we see that Black would definitely like to sacrifice the knight for the two central pawns (at least this is a critical line we must calculate). This would bring Black closer to the above endgame. An example line:

Now we see that Black's counterplay is very clear.
It is useful to verbalize specifically what Black wants to do, and what we need to prevent.

We must prevent Black from playing ...h5

The reader may wish to try once again to find the solution, spend up to 15 minutes.

Now, the final solution:

I am not surprised if I made mistakes in the endgame conversion, though the general idea is the same.


 That's all for now, I plan to have more examples in the future - but hopefully the thought process is clear.

Please leave a comment, until next time, happy chessing! 

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