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Comment by dmurray | Hacker News Reader

> the single most important basic ending

This just isn't right. According to de la Villa (whose book is a great trainer on this endgame among others) this balance comes up 1 time in 5000, compared to RPPvR or PPvP which each occurred more than 10x as often. Ok, some of those are trivial, but there are many more half-points to be had by studying those.

I have studied this endgame before to the point where I was confident in holding it (mostly based on the selected defences given by de la Villa, which I reckon cover almost all positions), but I confess I didn't practice it against a tablebase. I also lost this the one time I had it over the board.

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1 in 5000 seems very off. A quick search has it occurring in 1.7% of all games which sounds about right. [1] If he indeed said 1 in 5000, it might have been from a database with lots of quite low rated games.

There are two reasons I think it's one of (calling it the most was a bit of hyperbole) the most important basic endings.

One is that it's not only relatively frequent but also an endgame that just constantly sees the 'wrong' result.

The second point though is what I already mentioned - it really teaches you a lot about how a bishop and rook can play together. If you can genuinely internalize that ending, your play with these pieces, in all phases of the game, would just naturally improve. Again it's similar to the way that the B+N ending can help improve your play with those pieces.

I mean sure it's useful to know that R and f+h pawns v R is only a [difficult] draw, but that knowledge is not very useful outside of that exact scenario.

[1] - https://thechessworld.com/articles/endgame/chess-statistics-...

That link is the lowest quality article I've ever seen, but if it means anything, it seems to mean Rook and Bishop vs Rook, but both sides also have any number of pawns. Pure RB v R does not come up one game in 60 at any level, that's ridiculous. Has there ever been one in a World Championship match? Out of 1000+ games I can't think of any.

I've had R+F+h vs R several times, and the evaluation of it being important to another endgame countless more.

In looking at my old reference database (~300,000 good quality and relatively contemporary games at/before 2020) R+B v R with pawns on either side showed up 5.6% of the time. The exact ending with 0 pawns showed up 0.15% of the time. That's probably understating it since it's more likely to occur against relatively evenly matched players.

It's also going to depend on the style of the players. Caruana, for instance, had it at least 10 times including 4 wins (starting from theoretically drawn positions) against 2666 rated Guseinov, 2765 rated Radjabov, 2557 rated Gareyev, and even one kind of against 2809 rated Aronian. The one against Aronian needs an asterisk because they were playing with both sides having 1 pawn (in a still theoretically drawn position) and eventually Aronian voluntarily transposed into a completely lost RB v R ending.

So 1.6% is very much in the realm of possibility depending on the specifics of the dataset. 1 in 5000 is difficult to imagine by any composition. It might have been a typo in his notes and he meant 1 in 500? That probably is underestimating it, but it's at least an order of magnitude closer to the right ballpark.

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