Another endgame, no tablebases please

[Sven]

Well, my engine also doesn't show a very high score for white...
[...]
best move: h3-h4 time: 1:27.173 min n/s: 295.000 nodes: 25.200.567

+0.20 is really not much regarding the score of other engines in this position...

It would be interesting to know why your engine prefers 1.h4 although there is a plan for white that looks very strong (king to b6). What does your engine play after 1.Kb4 or 1.Kb5? And what after 1.Kd4?

Sven

[Robert Flesher]

I was referring to my original position, as his will never occur if the player/engine has any clue. I original position is a simple draw any 1600 player should know. I agree with the assessment of his position, but it is clear with knowledge that it need never happen. This was my point. A simple search should avoid any of those zugzwang positions.

So now I would like to learn a bit from your playing strength, maybe the authors of the strongest engines can learn a bit about rook endings, too

What is the simple plan which all those ELO 1600 players are aware of in order to draw easily when playing black in your original position?
[D]R7/P4r2/6p1/6kp/2K5/6PP/8/8 w - - 0 55[/D]

How does black prevent white from reaching the position Miguel showed above, in order not to need knowledge about that zugzwang situation?

What is the advice for black, in conformance to your strategy, after these first moves: 1.Kd4 Kf5 2.Ke3 Kg5 3.Ke4 - should black play Rg7, Rh7, Re7+, or Kf6 (they all allow white to cross the f-file with its king)? Or better play Rb7, and if yes, why?

So if black really plays 3...Rb7, now the white "surprise": 4.h4+ Kg4 5.Rg8. Will they play 5...Rxa6 and know how to draw after 6.Rxg6+ Kh3 7.Kf5, since they know that they should keep their black rook on rank 6 in order to avoid Kg6-Kxh5, and that they must not exchange rooks for instance on g3 or g5 in a wrong moment? Or are they even more clever, avoid that and play 5...Re7+ 6.Kd4 Rxa7 7.Rxg6+ Kf3, or 7...Kh3 8.Ke4 Rf7 with a simple draw?

Will all ELO 1600 players avoid this sequence of play: 1.Kd4 Kf5 2.Ke3 g5 3.Kf3 Ke5+ 4.Kg2 Kf5 5.Kh2, or will they know how to draw this position? 5...Kf6?? 6.g4 +-; 5...g4 6.Rh8 Rxa7 7.Rxh5+ Kg6 8.hxg4 - a simple draw? O.k., a tablebase draw, but is it simple to play for a weak player? And what about an engine: from the given starting position there are 15 plies until a 6-men ending is reached after 8.hxg4, will it be found by TB probe at that depth? Oops - you said "no TB please", so will the engine know it is a draw despite the +2 pawns minus double pawn penalty? Has it built-in knowledge about such rook endings?

It seems I have been underestimating the deep knowledge of all ELO 1600 players about the subtleties of rook endings until today ...

To be serious again, I think that it is quite a difficult task for even the strongest chess engines to find the draw, since there is no support yet from 7- or even 8-men TBs (and will probably not be for a very long time). A "simple search" as you claim seems to fail revealing the truth within the current limitations of search depth, and I think it is due to the fact that positions like this have many subtrees for which evaluating them to draw requires very special and complex knowledge, for instance "give up the pawn, give horizontal checks from long distance and then either win back the pawn, convert to a known draw, or chase the king around the open board".

Sven

Quite the loquacious response! Also, with a dash of condescension. Remember, I am the one who posted this position. However, perhaps some follow-up should be done. Here is a hint, this position can occur if white plays what "I" believe is best. Which looks to be a draw to me, correct me if wrong (I dare you). I'll leave it up to you to solve your own questions, or post a winning line for me to try and refute. However, subsequently, I think you should read "DVORETSKY'S ENDGAME MANUAL". Then look at the position again.

[d]8/r7/4K1R1/7p/7P/5kP1/8/8 w - - 0 0

[michiguel]

I was referring to my original position, as his will never occur if the player/engine has any clue. I original position is a simple draw any 1600 player should know. I agree with the assessment of his position, but it is clear with knowledge that it need never happen. This was my point. A simple search should avoid any of those zugzwang positions.

So now I would like to learn a bit from your playing strength, maybe the authors of the strongest engines can learn a bit about rook endings, too

What is the simple plan which all those ELO 1600 players are aware of in order to draw easily when playing black in your original position?
[D]R7/P4r2/6p1/6kp/2K5/6PP/8/8 w - - 0 55[/D]

How does black prevent white from reaching the position Miguel showed above, in order not to need knowledge about that zugzwang situation?

What is the advice for black, in conformance to your strategy, after these first moves: 1.Kd4 Kf5 2.Ke3 Kg5 3.Ke4 - should black play Rg7, Rh7, Re7+, or Kf6 (they all allow white to cross the f-file with its king)? Or better play Rb7, and if yes, why?

So if black really plays 3...Rb7, now the white "surprise": 4.h4+ Kg4 5.Rg8. Will they play 5...Rxa6 and know how to draw after 6.Rxg6+ Kh3 7.Kf5, since they know that they should keep their black rook on rank 6 in order to avoid Kg6-Kxh5, and that they must not exchange rooks for instance on g3 or g5 in a wrong moment? Or are they even more clever, avoid that and play 5...Re7+ 6.Kd4 Rxa7 7.Rxg6+ Kf3, or 7...Kh3 8.Ke4 Rf7 with a simple draw?

Will all ELO 1600 players avoid this sequence of play: 1.Kd4 Kf5 2.Ke3 g5 3.Kf3 Ke5+ 4.Kg2 Kf5 5.Kh2, or will they know how to draw this position? 5...Kf6?? 6.g4 +-; 5...g4 6.Rh8 Rxa7 7.Rxh5+ Kg6 8.hxg4 - a simple draw? O.k., a tablebase draw, but is it simple to play for a weak player? And what about an engine: from the given starting position there are 15 plies until a 6-men ending is reached after 8.hxg4, will it be found by TB probe at that depth? Oops - you said "no TB please", so will the engine know it is a draw despite the +2 pawns minus double pawn penalty? Has it built-in knowledge about such rook endings?

It seems I have been underestimating the deep knowledge of all ELO 1600 players about the subtleties of rook endings until today ...

To be serious again, I think that it is quite a difficult task for even the strongest chess engines to find the draw, since there is no support yet from 7- or even 8-men TBs (and will probably not be for a very long time). A "simple search" as you claim seems to fail revealing the truth within the current limitations of search depth, and I think it is due to the fact that positions like this have many subtrees for which evaluating them to draw requires very special and complex knowledge, for instance "give up the pawn, give horizontal checks from long distance and then either win back the pawn, convert to a known draw, or chase the king around the open board".

Sven

Quite the loquacious response! Also, with a dash of condescension. Remember, I am the one who posted this position. However, perhaps some follow-up should be done. Here is a hint, this position can occur if white plays what "I" believe is best. Which looks to be a draw to me, correct me if wrong (I dare you). I'll leave it up to you to solve your own questions, or post a winning line for me to try and refute. However, subsequently, I think you should read "DVORETSKY'S ENDGAME MANUAL". Then look at the position again.

[d]8/r7/4K1R1/7p/7P/5kP1/8/8 w - - 0 0

The point is that you cannot evaluate the original position statically. Even a human player needs to calculate quite a bit to conclude that the position is a draw. If a human player needs to do that, why not a engine? Black needs to solve some tactical hurdles before calling it a draw. That is what makes the statical evaluation impossible. This is not a fortress or a theoretical position and the clear draw comes after many many moves. And yes, a 1600 player will have a tough time drawing this position. For instance, most of them will make a mistake in the following position, losing.

[D]R7/P4r2/6p1/5k1p/8/5KPP/8/8 b - - 0 1

[Robert Flesher]

I was referring to my original position, as his will never occur if the player/engine has any clue. I original position is a simple draw any 1600 player should know. I agree with the assessment of his position, but it is clear with knowledge that it need never happen. This was my point. A simple search should avoid any of those zugzwang positions.

So now I would like to learn a bit from your playing strength, maybe the authors of the strongest engines can learn a bit about rook endings, too

What is the simple plan which all those ELO 1600 players are aware of in order to draw easily when playing black in your original position?
[D]R7/P4r2/6p1/6kp/2K5/6PP/8/8 w - - 0 55[/D]

How does black prevent white from reaching the position Miguel showed above, in order not to need knowledge about that zugzwang situation?

What is the advice for black, in conformance to your strategy, after these first moves: 1.Kd4 Kf5 2.Ke3 Kg5 3.Ke4 - should black play Rg7, Rh7, Re7+, or Kf6 (they all allow white to cross the f-file with its king)? Or better play Rb7, and if yes, why?

So if black really plays 3...Rb7, now the white "surprise": 4.h4+ Kg4 5.Rg8. Will they play 5...Rxa6 and know how to draw after 6.Rxg6+ Kh3 7.Kf5, since they know that they should keep their black rook on rank 6 in order to avoid Kg6-Kxh5, and that they must not exchange rooks for instance on g3 or g5 in a wrong moment? Or are they even more clever, avoid that and play 5...Re7+ 6.Kd4 Rxa7 7.Rxg6+ Kf3, or 7...Kh3 8.Ke4 Rf7 with a simple draw?

Will all ELO 1600 players avoid this sequence of play: 1.Kd4 Kf5 2.Ke3 g5 3.Kf3 Ke5+ 4.Kg2 Kf5 5.Kh2, or will they know how to draw this position? 5...Kf6?? 6.g4 +-; 5...g4 6.Rh8 Rxa7 7.Rxh5+ Kg6 8.hxg4 - a simple draw? O.k., a tablebase draw, but is it simple to play for a weak player? And what about an engine: from the given starting position there are 15 plies until a 6-men ending is reached after 8.hxg4, will it be found by TB probe at that depth? Oops - you said "no TB please", so will the engine know it is a draw despite the +2 pawns minus double pawn penalty? Has it built-in knowledge about such rook endings?

It seems I have been underestimating the deep knowledge of all ELO 1600 players about the subtleties of rook endings until today ...

To be serious again, I think that it is quite a difficult task for even the strongest chess engines to find the draw, since there is no support yet from 7- or even 8-men TBs (and will probably not be for a very long time). A "simple search" as you claim seems to fail revealing the truth within the current limitations of search depth, and I think it is due to the fact that positions like this have many subtrees for which evaluating them to draw requires very special and complex knowledge, for instance "give up the pawn, give horizontal checks from long distance and then either win back the pawn, convert to a known draw, or chase the king around the open board".

Sven

Quite the loquacious response! Also, with a dash of condescension. Remember, I am the one who posted this position. However, perhaps some follow-up should be done. Here is a hint, this position can occur if white plays what "I" believe is best. Which looks to be a draw to me, correct me if wrong (I dare you). I'll leave it up to you to solve your own questions, or post a winning line for me to try and refute. However, subsequently, I think you should read "DVORETSKY'S ENDGAME MANUAL". Then look at the position again.

[d]8/r7/4K1R1/7p/7P/5kP1/8/8 w - - 0 0

The point is that you cannot evaluate the original position statically. Even a human player needs to calculate quite a bit to conclude that the position is a draw. If a human player needs to do that, why not a engine? Black needs to solve some tactical hurdles before calling it a draw. That is what makes the statical evaluation impossible. This is not a fortress or a theoretical position and the clear draw comes after many many moves. And yes, a 1600 player will have a tough time drawing this position. For instance, most of them will make a mistake in the following position, losing.

[D]R7/P4r2/6p1/5k1p/8/5KPP/8/8 b - - 0 1

I never said you could. I said to me it is clear it is a draw and using simple rook and pawn endgame knowledge it should be easy. I also, never stated calculation was not needed, I looked at the position for several hours. I concluded with best play black MUST give up to a pawn to try to a win, not saying a swindle could not happen otherwise. I could be wrong, this is only my opinion. You could try to prove me wrong.

My original post is that engines struggle because they must calculate the things most if not any strong player knows. Such as, avoid any checks, zugzwang, distant opposition, rank and file control, etc, etc. Again, I'll refer you to DVORETSKY'S ENDGAME MANUAL, it teaches principals that once learned make endgame like this one much easier. However, that being said, rook and pawn endgames are generally extremely deep and complex and I lose to my engines all the time. This one however , is much easier. Quod erat demonstrandum

[Sven]

Quite the loquacious response! Also, with a dash of condescension. Remember, I am the one who posted this position. However, perhaps some follow-up should be done. Here is a hint, this position can occur if white plays what "I" believe is best. Which looks to be a draw to me, correct me if wrong (I dare you). I'll leave it up to you to solve your own questions, or post a winning line for me to try and refute. However, subsequently, I think you should read "DVORETSKY'S ENDGAME MANUAL". Then look at the position again.

Going down to the personal level due to lack of arguments is not the way to go. Also I cannot see any "condescension" in my previous post. You made a statement about how "simple" this position would be in your opinion, and Miguel pointed out his opinion that it were in fact quite difficult to evaluate without deep search. After you insisted I thought it were necessary to show in detail which parts of the analysis may be important to decide whether this is a "simple draw" or not.

The position that is reached after what you believe is best for white is indeed a draw, and indeed quite simple to play for black once it has been reached. Please consider, though, how deep the analysis from your original position has to go in order to come to that point. It is 16 plies. How many percent of, say, ELO 2200 players are able to identify that position as belonging to their main line of analysis - if it really is, what I assume here since it looks plausible - *in an OTB game*, and state substantially that it is a draw and why?

I am still pretty convinced that rook endings like this one require deep analysis and substantial chess knowledge to be evaluated correctly, both by humans and engines. Human master players are much better at it but neither ELO 1600 nor players on my own level of strength, around 1900, usually have that ability to spontaneously classify such endgames as "simple draw" *and say correctly why*. Maybe you are a stronger player, I don't know, but even then it does not change my opinion about typical abilities of weaker players, like myself. I also see nothing condescent in objectively stating existing differences in chess playing capabilities between "stronger" and "weaker" players.

One last remark: it is possible that my writing style in my previous post was not adequate for expressing my intentions, so I want to apologize for that, also for my somewhat "lengthy" writing. You'll probably know that sometimes it is not easy to put many thoughts into few words.

Sven

[Sven]

And yes, a 1600 player will have a tough time drawing this position. For instance, most of them will make a mistake in the following position, losing.
[D]R7/P4r2/6p1/5k1p/8/5KPP/8/8 b - - 0 1

Oh yes, 1...g5?? 2.g4+ +- may be quite tempting. Still White must play carefully to win the won position now.

Sven