A Special Class of Rook and Pawn Endings  Part 4

A Special Class of Rook and Pawn Endings Part 4

Jun 23, 2016, 4:49 AM |

We've been examining KRP vs KR positions where the Pawn is as far as possible from queening.  If White has the Pawn, that means it starts on the 2nd rank.  Whether or not Black can draw mostly has to do with whether his King can get close enough to the Pawn to impede its progress.  Thus, when the black King is cut off by 3 or more files and is on the 8th or 7th rank, it's usually far enough away White to win.  What happens if the King is cut off by only two files?

There are a couple of cases where White can force a win, but it's not easy.  In practical situations between masters, Black is likely to defend succesfully perhaps as much as half the time.

The first case I know of where White can win is with the Pawn on c2 and Black's King cut off on f8 like this:

According to Tablebase, White to move wins in 63, Black to move, it's theoretically drawn.  If we move everything one file to the left or to the right, the position is also theoretically drawn.

Let's look at a practical example of me playing this position vs a chess engine, and then compare that to a line of best play.



This position is quite difficult, and I haven't really mastered it yet. It took me several tries to win this one on my own.  I'd say I might win this one 25% of the time vs the computer, and less than 10% of the time vs Tablebase.   In this one example I walked through about eight nodes where there was only one move that maintained a win.  Some of those were easy moves, and others were beyond subtle and I was just lucky.


Themes and strategies that we have discussed before were present.  Let me re-iterate some of them.

  1.  Rook ahead of Pawn

  2.  Rook cutting King off at 5th rank and confining it to the rear

  3.  Kings facing off with threat to drive it back a file.

  4.  Waiting moves with the Rook to set up an effective King walk.


 There's one other King placement that's worth examining.  If we move Black's King all the up to f2 where it is attacking the Rook, White to move wins in 53.  The reason is, as discussed before, that the King is "offside" and can be confined to the back of the board.



It took me a couple tries to win this without any help, but it's definitely less difficult than the previous position.  It helps to view the confinement of the defending King as a temporary measure.  As the game goes on, it gets more room but it's never enough, and that is the key. 
Thinking in practical terms, these positions with two file separation are difficult to win against strong opposition, but I believe most players, even titled players, are not capable of defending perfectly.  For that reason, don't despair if it looks like the game slipped into something drawish.  There's plenty of opportunity for the defender to botch it.
Next time, I will examine one or two cases where the extra Pawn is a Rook pawn.