... in the end it all comes down to ensuring adequate checking distance.John Nunn, Secrets of Practical Chess
It was Tarrasch's idea. To put these two diagrams side by side, I mean. I first saw them like this in Emms' Survival Guide and at some time in between those two authors published their books Keres (and no doubt many others) did it too.
'Checking distance'; 'checking room'; 'distance effectiveness'. Call it what you will, it's probably the single most important principle of rook and pawn against rook endings there is. And, yes, I am including 'rook behind the pawn' when I say that.
Checking distance is important in theory and often determines the outcome of games in practice. As we'll see, it was Black's lack of understanding of the concept that cost him a win in the Stephens - Balaji ending from the British Championship which we looked at last week.
Rooks are long range pieces. I've read that in a million different places. What it seems to mean when there's only one pawn left on the board is that it's usually best to keep your rook as far away from the enemy king as possible. Then you can still throw in your checks as and when necessary, but you're far enough away that the king can't harass you in return.
So where's the line? At what point does 'far away' become 'far enough'? Turns out it's three squares.
It's not just a side-to-side thing either. It's up and down as well. Open up The Book and you'll see Levenfish and Smyslov's introduction includes these two diagrams. Actually they have them without the black king on the board which rather emphasises the point that, once again, with enough room the black rook can stop the pawn by itself.
So much of the theory of how to play rook and pawn against rook positions rests on checking distance it's almost impossible to overstate its importance. Not Philidor maybe, but practically everything else. The short-side defence, Lucena (both winning it and getting there), Ending 57. All these 'fundamentals' are built on a foundation of checking distance. By extension, all the more complex positions that can be reduced to the theoretical ones must be too.
Black to play
And so, after the theory, we finally reach the practical. Stephens - Balaji, British Championships 2013 (3). Black is about to play 78 ... Rc1. In one sense there's nothing wrong with this move - Black's still winning after all - but we're trying to queen that pawn aren't we so why not just 78 ... d3?
Check Nalimov and you'll see that after the move played in the game mate is only three moves further away than after the pawn move that I'm suggesting as an improvement. To focus on the number, though, is rather missing the point. There are only two squares between White's rook and Black's king so we know it doesn't have checking room. It can't hurt us. So if there's no need to block a check why bring the rook to the c-file at all?
Balaji's move isn't some kind of chessicle snake that will send him backwards a few moves. Rather, with ... Rc1 he's taking himself off on the wrong track altogether. One that will eventually take him over the line from 'win' to 'draw', but not before he misses one last just chance to get back on the right road.
Black to play
Move 81. Black's about to play ... Kc3, but why? We know that White's rook isn't far enough away so why not get Black's rook doing something more useful. ...Rc8, ...Re8 and Black's win is straightforward. ... Kc3 still wins - just - but it gives Black a chance to go wrong and he soon did.
It could have been different. For the Stephens - Balaji endgame, just like a lot of others, the result came down to checking distance.
Rook and pawn Index