How do you assess this position?

[Dr.Wael Deeb]

Hi Wael.
I think you are about right in the assessment...

Thanks

[Andre]

What about Rb4 then
Rxa4 Nxa4
Rxa4 Rxc3
Rb4 etc...
we push the pawn to b7 then Black will be in zugzwang if Rook comes to b8 letting White King to invade via f4 etc...

[Lyudmil Tsvetkov]

What about Rb4 then
Rxa4 Nxa4
Rxa4 Rxc3
Rb4 etc...
we push the pawn to b7 then Black will be in zugzwang if Rook comes to b8 letting White King to invade via f4 etc...

On Rb4 black replies simply Ra8.

[Don]

OK, no one posting, so probably no one is interested, although it seems to me that it is a decent position, or even a nice position.

[D]2r5/8/1n6/1P1p1pkp/p2P4/R1P1PKP1/8/1R6 w - - 0 1

I will give you my feedback on the position then.
I think the position could be judged as a straightforward draw, because,
strange as it might seem, this is actually a fortress. Believe me or not, all the files are closed, although there is only a single pair of blocked pawns.
the a file is closed, because the a4 passer is well protected by the knight, or alternatively, by the rook and the knight
the b files is closed, because the black knight blocks the white passer, and it is important that the blocking piece can not be attacked by white, so you can consider its blocking position permanent
the c file is closed, because c3 is a backward-fated pawn (kind of, because the knight almost acts as a second pawn controlling the square in front of c3; and a backward-fated pawn, of course, will be a pawn the square in front of which is controlled by 2 enemy pawns, while no friendly pawns can support its advance, so actually it can not advance without being lost) ; but also, in many variations there is the possibility to play the black rook on c4, permanently blocking c3, as the rook can not be attacked
the d file is closed because of a pair blocked pawns
the e file is blocked, because e3 is a backward-fated pawn
the f file is blocked, because the f5 pawn could easily be protected with the rook, and the f4 square is controlled by the black king
the g file is blocked, because g3 is backward-fated
the h file is blocked, because the h5 pawn can easily be protected by the rook, and the h4 square is controlled by the black king

So, it would seem, 8 blocked files will most certainly assure a draw. And that would be the right positional solution. But, even if the position is not considered as a fortress, engines' score should be pretty much close to an equal one, only based on calculating the pawn structure appropriately. White has 4 backward-fated pawns, actually all except for the passer on b5. A backward-fated pawn can be worth a penalty of some 35 centipawns, higher in the endgame, so that 4 such pawns would make a pretty big difference. At the same time, black has only one such pawn - on f5. Additionally, the knight on b6 is an excellent blocking piece and might be worth some 25-30 centipawns, blocking a separate passer. The white rook on a3 is also blocking an enemy passer, but it could not be worth more than 5 centipawns for its blocking role, as it is awkwardly placed there and easily expelled. The black knight on b6 also enjoys extremely good functionality - it blocks the enemy passer, protects its own passer, defends the d5 pawn and controls the c4 square at the same time. It is true that black has nominally 3 isolated pawns, but they are inaccessible to attacks by enemy pieces (or easily defended), so most probably their penalties should be somewhere halved. Overall, black almost equalizes the score.
For some reason engines (at least in my blitz tests) have utter disdain for backward-fated pawns (and those are quite different from simple backward pawns) as if they did not exist at all. But actually, they are quite important, and it is really easy to draw or even win against a top engine, using the knowledge of only that factor.

Looking at possible breakthroughs, all of them seem to fail or be dangerous:
c4 could not be allowed at all by playing the black rook on c4
e4 would give black 2 advanced separate passers after dc4, and possibly, in many variations Nc4, a3,e3 with a nice counterplay
g4 would be met by fg4 and the 2 connected passers, able to advance easily, while some deficiencies in the white pawn structure still remain, would be a dangerous continuation for white

Doubling the rooks along the h file is met by Rh8-h7 and no headway there
Transferring the white king to the queen side looks awkward at the least.

The point that I am posting this position is only because I think some brainstorming would not hurt anyone, but, if anyone is unhappy with my posts, please, tell me so. The other day I was on the Russian chesspro site (btw, a very good chess site with an English section) and some grandmasters commented on the game Anand-Kramnik from the London Chess Classic, aided by engines. Throughout the game the engines persistently found better continuations, lines humans would not play or even consider, even only on the assumption that they are unclear, with a lot of simultaneous attacks, although they might actually be quite good, but the game came to a climax with finally all 8 pairs of pawns being blocked, a straightforward draw; and grandmasters started laughing at engines' evaluations, thinking white was still much better (probably because of some space advantage, etc.). And truly, it makes me laugh too, because it is simply a bit ugly - being able to evaluate properly much more complex positions, but not able to evaluate very simple ones. This could only lead to a certain amount of depreciation for the engine play, although overall, engines play fabulous chess.

Again, my only point was some brainstorming excercise. Still, I would appreciate some comments on the position - what do you think about it? And maybe some users will be able to run some engines through the position and post some results: are there any engines that would show a score 0.0, or close to equal (50 centipawns advantage for white, but even lower than a full pawn would qualify).

Best regards,
Lyudmil

I'm pretty sure this is still a win for white if white is willing to take some chances. This is something computers are not good at, but the idea is to be willing to give up something to break through.

But it's complicated - I cannot say that for sure.

Don

[Don]

What about Rb4 then
Rxa4 Nxa4
Rxa4 Rxc3
Rb4 etc...
we push the pawn to b7 then Black will be in zugzwang if Rook comes to b8 letting White King to invade via f4 etc...

On Rb4 black replies simply Ra8.

I played a 30 minute + 5 second match between Komodo and Houdini 1.5 and Komodo very quickly gives up the rook for the knight and wins easily.

However, I am still not sure this is a win. Houdini was not forced to take the bait and could have just sit on the position in this case.

At a longer time control Houdini will not take the bait. I'm going to reverse colors to see what happens.

[pgn]
[Event "Computer Chess Game"]
[Site "greencheeks"]
[Date "2013.01.15"]
[Round "-"]
[White "Komodo"]
[Black "Houdini 1.5"]
[Result "*"]
[TimeControl "600+5"]
[FEN "2r5/8/1n6/1P1p1pkp/p2P4/R1P1PKP1/8/1R6 w - - 0 1"]

1. Rba1 Rc7 2. Rxa4 Nxa4 3. Rxa4 Rxc3 4. Rb4 Rc7 5. b6 Rb7 6. Rb5 Kf6 7.
Rxd5 Rxb6 8. Kf4 Kg6 9. Rxf5 Rb4 10. Rg5+ Kh6 11. Rg8 Kh7 12. Rc8 Kg7 13.
Rc5 Kg6 14. Rc6+ Kg7 15. Kg5 Kf7 16. Rc5 Rb3 17. Re5 Rb1 18. Kxh5 Kf6 19.
Kg4 Rb2 20. e4 Rb4 21. Rd5
[/pgn]

[Don]

Correction: This was houdini 3 I was using. I configured the polyglot file with the old houdini 1.5 name but it is using the houdini 3 binary.

What about Rb4 then
Rxa4 Nxa4
Rxa4 Rxc3
Rb4 etc...
we push the pawn to b7 then Black will be in zugzwang if Rook comes to b8 letting White King to invade via f4 etc...

On Rb4 black replies simply Ra8.

I played a 30 minute + 5 second match between Komodo and Houdini 1.5 and Komodo very quickly gives up the rook for the knight and wins easily.

However, I am still not sure this is a win. Houdini was not forced to take the bait and could have just sit on the position in this case.

At a longer time control Houdini will not take the bait. I'm going to reverse colors to see what happens.

[pgn]
[Event "Computer Chess Game"]
[Site "greencheeks"]
[Date "2013.01.15"]
[Round "-"]
[White "Komodo"]
[Black "Houdini 1.5"]
[Result "*"]
[TimeControl "600+5"]
[FEN "2r5/8/1n6/1P1p1pkp/p2P4/R1P1PKP1/8/1R6 w - - 0 1"]

1. Rba1 Rc7 2. Rxa4 Nxa4 3. Rxa4 Rxc3 4. Rb4 Rc7 5. b6 Rb7 6. Rb5 Kf6 7.
Rxd5 Rxb6 8. Kf4 Kg6 9. Rxf5 Rb4 10. Rg5+ Kh6 11. Rg8 Kh7 12. Rc8 Kg7 13.
Rc5 Kg6 14. Rc6+ Kg7 15. Kg5 Kf7 16. Rc5 Rb3 17. Re5 Rb1 18. Kxh5 Kf6 19.
Kg4 Rb2 20. e4 Rb4 21. Rd5
[/pgn]

[Don]

Correction: This was houdini 3 I was using. I configured the polyglot file with the old houdini 1.5 name but it is using the houdini 3 binary.

I'm not playing this out again with Houdini taking white. This one is going to be a long game but I'll make a prediction - I think Houdini will win with pressure from the 50 move rule.

[Don]

Houdini easily wins too but just in a different way. Both wins I believe were based on an error from the other side.

So it's clear that neither program understands what is going on.

[pgn]
[Event "Computer Chess Game"]
[Site "greencheeks"]
[Date "2013.01.15"]
[Round "-"]
[White "Houdini 3"]
[Black "Komodo"]
[Result "1-0"]
[TimeControl "600+5"]
[FEN "2r5/8/1n6/1P1p1pkp/p2P4/R1P1PKP1/8/1R6 w - - 0 1"]

1. Rba1 Rb8 2. R3a2 Rb7 3. Rh2 Re7 4. Rah1 Rh7 5. Ra2 Rc7 6. Rc1 Rc8 7. Kf2
Kg4 8. Ra3 Ra8 9. Rb1 Ra7 10. Raa1 Rc7 11. Rc1 Rb7 12. Ra2 Rc7 13. Ra3 Ra7
14. Rb1 Rc7 15. Rh1 Rb7 16. Raa1 Nc4 17. Rhb1 Nb6 18. Rc1 Nd7 19. c4 dxc4
20. Rxa4 Rxb5 21. Raxc4 Nf6 22. Rc7 Ne4+ 23. Kg2 Kg5 24. Rc8 Ra5 25. Kf3
Nd2+ 26. Ke2 Ne4 27. Rg8+ Kf6 28. Rc6+ Kf7 29. Rb8 Ra2+ 30. Kd1 Ra1+ 31.
Kc2 Ra7 32. Rh8 Kg7 33. Rxh5
{User adjudication} 1-0
[/pgn]

[Lyudmil Tsvetkov]

Hi Don.
Many thanks for taking part in the discussion!
And I am 99% sure it is a draw with best play from white, considering the 50-moves rule and all possible breaks.

I would be glad to see some concrete variations, proving that white wins. But again, in no way should black return the exchange, better stay with the knight, some dangerous passers and a very active king. c4 seems to be the only plausible alternative for a break, and then I suggest that the black king is transferred to the queen side to help the advance of the passers that will appear.