In this series, I'm examining KRP vs KR positions where the strong side's Pawn is as far as possible from queening. This time, we will look at some cases where the defending King is cut off by three files. If the Pawn were up to the 5th rank, that would usually be an easy win, but with the Pawn on the 2nd rank, things are more difficult.
Let's start by keeping the Pawn on b2 and placing Black's King on f8 like this:
Tablebase reveals that with White to move it's mate in 50. The difficulty is only moderate, however, because it's not that hard to find a good plan. That is especially true if you have seen the previous examples. Winning positions like this involves making rather subtle waiting moves at the right points. Usually the waiting move is a Rook along the file that cuts off the defending King.
The idea behind the waiting moves is based on this. Black has to move either his Rook or his King. Once that move is made, the path to improving our position becomes clearer. With that in mind, take a look at this example where I am playing against Shredder at full strength.
As in other examples, neither side is playing with Tablebase perfection. When better moves were possible, they are shown in the game score. The technique used here bears simiiarity to previous examples. There is some explanation of this in the annotations above.
Now, let's think about different King placements for Black. If the King goes to f7, White to move wins in 51. If the King is on f6,f5,or f4, the game is theoretically drawn. White just doesn't have enough time to move his Pawn, even to b3. If Black's King is on f3 or f2, White to move once again wins, in theory. Why? The King is "offside", and can now be confined to the irrelevant side of the board. Let's look at what happens when Black's King is on g3. White to move, wins in 43. I explain some of this in the annotations in the example below.
So, now we come to another strategic theme in winning this class of Rook and Pawn endgames. It has to do with the placement of the defending King.
When the defending King comes to the 4th rank or further forward, consider cutting it off with the Rook to confine it to the back of the board.
Unfortunately, there are many qualifying factors to whether Black's King should be cut off in this manner. The strategy might not work if the Pawn is a Rook Pawn, a special case that I'll cover later. This approach also won't work if the White King placement is wrong. In general, the White King has to be 4th rank or further forward, and it has to be able to protect and advance the Pawn. The foregoing example illustrates this fairly well.
One last remark before I close this post. I could show examples of 3-file separation where White wins with other files. I could put the Pawn on c2 and confine Black's King to the g-file. The strategy is similar to other cases I've shown, and the evaluation of King placement is also similar. Thus, if the defending King is on the 6th, 5th, or 4th rank, it's often a theoretical draw. Anyway, I don't see much point in covering any other 3-file cases.
In the extreme case of separating the defending King from the Pawn by two files, the placement on the board make quite a lot of difference. I will cover this in the next post.