8

With the missing g and e pawns still on the board and a roughly symmetric position, I made a mistake that led to 17 moves of what I think of as quite difficult defense. My opponent walked into the following fork and then resigned.

 [Title "Game's Final Position"] 
 [SetUp "1"]
 [FEN "8/5pp1/7p/1n1R3k/4PP1P/8/8/r3BK2 w - - 6 1"]

I know that I definitely would not have resigned in that position.

Is the above position won for white?



Conceivably, black could play Kg6 and try to put together something like a fortress, or even play g5 immediately after Rxb5. However, I believe the correct continuation would be

1 ... Kg4 2. Rxb5 Kxf4 3. Rf5+ Kxe4 4. Rxf7 g5 5. h5, resulting in the position

 [Title "End of My Main Line"] 
 [SetUp "1"]
 [FEN "8/5R2/7p/6pP/4k3/8/8/r3BK2 w - - 6 1"]

with black to move.

From tablebases (e.g. this site), I know that if I instead played 5. hxg5 and black responded with hxg5 then the position would be a draw. In fact, even if all three remaining pawns disappeared and it became my move, the position would still be a draw. Thus, white's strategy at the end of my main line presumably involves threatening/trying to win the pawn on h6, possibly after exchanging rooks.


(I don't know whether or not the "rook endgame" tag is appropriate, since there's also a bishop on the board.)

  • The final variation you give seems to be the only way to resist (the 1...Kg6 you suggest is nonsense however). But in the final position after 1 ... Kg4 2. Rxb5 Kxf4 3. Rf5+ Kxe4 4. Rxf7 g5 5. h5 even if it is hard to demonstrate a win for white the general idea is that white will be able to consolidate by bringing his king near to its pawn and win in the long run. But you are right that resignation was clearly premature. – Niels Aug 21 '14 at 12:20
  • 2
    The "mainline position" is won for White, but the lines are too long to post them here. Is there a concrete problem you face in converting this position into win? As for the position after the blunder ( Rd5+ ), it is still won for White but it does require precise execution as Black will significantly reduce the number of pawns with 1...g5, followed by ...f6. – AlwaysLearningNewStuff Aug 21 '14 at 13:30
  • A gut feeling is that Black would have a chance against a light squared Bishop. With a dark-squared one, Black pawns are doomed, and since H8 is also dark, White has a luxury to exchange Rooks. No concrete variants, but all odds are for White to win. – user58697 Sep 4 '14 at 7:18
2

According to my analysis, it seems like a clear win. Black can't force the exchange of the remaining white pawn, White has the Bishop of the appropriate color, and Black can't prevent White to improve the position of its pieces.

An important tactical finesse:

1..Ke5 2.Kg2 Rxe1 3. Re7+, winning the Rook.

Another important idea:

1..g4 2. Rf6 g3 3. Rg6! (3. Rxh6 g2+ 4. Kxg2 Rxf1 5. Rf6 =) 3..Ra5 4. Rg4+

and the g pawn falls.

(Note that 2. Kg2 is also possible, with the same idea as above.)


It should be a matter of time for Black to lose its remaining pawns, since the black King is cut off from them. I can't offer any concrete lines, so perhaps I'm wrong here. But what I know is that

W: Kf1, Be1, Rh6, h5
B: Ra1, Kf5

is a win in the tablebases. It does not seem to be possible to prevent White to play Rh8 and h5-h6, after which the pawn is immune. As soon as it gets attacked by some Rh2, White has Rg8+, repeating the same tactical theme as above, or Bd2, protecting the pawn directly.

I've played some games with an extra Black pawn, and I have yet to save one game against Stockfish. One annoying bug of having a pawn on g4 is that black King can't move on g4.

0

Stockfish gives your "end of my mainline position" as winning for white(+2.62). I am attaching the whole line below. It does seem that while the rook protects the bishop, the white king can quickly head over to the black pawn chain.

Score: 2.62
Best: 1. ... Kg4   Ponder: 2. Rxb5
Time: 31.4s   Depth: 16
Server: srv01   CPU #1: 24%
Engine: Stockfish 1.8 64bit

1. ... Kg4 2. Rxb5 Kxf4 3. Rf5+ Kxe4 4. Rxf7 g5 5. h5 Ra6 6. Kg2 Rc6 7. Kg3 Kd5 8. Kg4 Rc4+ 9. Kf3 Rc1 10. Re7 Rb1 11. Bf2 Rb3+ 12. Be3 Rc3 13. Kg4 Ra3

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