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Evaluation of exchange sacrifice: How good is White's compensation after the exchange sacrifice on move 19? Seems the position is about even to me but Black might have more issues to solve. I am thinking it is Whites best winning chance as opposed to having just liquidated the queen-side pawns.

[FEN ""]
1.c4 Nf6 2.Nc3 g6 3.g3 Bg7 4.Bg2 O-O 5.e4 d6 6.Nge2 c5 7.O-O Nc6 8.d3 a6 9.h3 Rb8 10.a4 Ne8 11.Be3 Nd4 12.Rb1 Bd7 13.b4 Ne2 14.Nxe2 cxb4 15.Rxb4 b5 16.cxb5 axb5 17.Qb1 Nc7 18.Rc1 Na6 19.Rb5 Bb5 20.axb5
Herb
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Ywapom
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  • My first impression was that it might be white's best losing chance. I would need strong compie assistance to believe black is the one in trouble. – hoacin Jun 14 '18 at 17:34
  • White must have intended this in advance because moving the Rook on move 19 just loses. Given two Bishops, an advanced passer, a lead in development and no stable post for the Black Knight, this looks like the sort of thing that Kramnik wins every time. – Philip Roe Jun 14 '18 at 20:42
  • @PhilipRoe Sure, but he could play 18.ab5. This is just a theoretical question. Lines without the exchange sac seem to all liquidate the queen-side pawns which looks very drawish. – Ywapom Jun 14 '18 at 20:46
  • Your pgn is a bit unclear, for example 11... Nxd4 when nothing had moved to d4, or 13.. Ne2 should be Nxe2 – Hockeyfan19 Jun 15 '18 at 12:54
  • @Hockeyfan19 That was my bad, when fixing the original pgn to get the board to display. I've corrected it. – Herb Jun 15 '18 at 16:16
  • Much better, though black move 13 should also be nx I think. – Hockeyfan19 Jun 15 '18 at 16:21

3 Answers3

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This exchange sacrifice would be good if you could coordonate your pieces in order to support the passed b-pawn. In this given position, however, it looks like you are one tempo short and the pawn will be a target: 20...Qa5 and then

21.Nd4 [21.Nc3 is quite the same] Bxd4 22.Bxd4 Rxb5 and Black should win.

21.b6 Nc5 22.Bxc5 dc5 23.b7 [I see nothing else to hold on the pawn] Qa7 [or 23...e5 to prevent the opening of the g2-b7 diagonal] 24.e5 Bxe5 and the big passer gives practical chances but Black is clearly for choice.

Probably White would have reached a much better version of the game with 18.Nd4!? instead of 18.Rc1.

Evargalo
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  • It was my feeling that White is a tempo short as well. – Ywapom Jun 15 '18 at 15:34
  • Maybe White has to go for 20...Qa5 21.b6 Nc5 22.Qc2 with the idea of trading the b-pawn for Blacks's d-pawn. White is worse but hopes to at least keep a pawn for the exchange. – Ywapom Jun 15 '18 at 15:46
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That's not an easy question. At this point in the game the compensation must come in terms of concrete continuations. Simply relying on intuition is not enough. Ok, well, white has got the two bishops and the passed pawn. But are there objective plans to push forward? This has to be analyzed deeply to provide a deterministic answer. Otherwise it will be eyeballing only.

There are ideas of Nd4 aiming for c6. Idea of e5 push to immediately utilize the light-colored bishop. But as I said, one must come up with concrete follow-up after ...Nc7

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I would say that the rook sac was correct. Retreating to b3 just allows bxa4, attacking the rook with tempo and creating a very strong passed pawn that has a lot of support. The fianchetto'd bishop on g7 even controls it's queening square. Giving up a rook for a bishop and pawn, and creating a passed pawn of their own is the best option for white.

Hockeyfan19
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  • Hmm, you asked how good it was though. On that move it was the best move. If you want to know if this is top level opening theory then no, there were some misplays on both sides before the exchange sac came up. – Hockeyfan19 Jun 15 '18 at 15:28
  • In particular white is overall worse in this line. He has some play but black is certainly better. – Hockeyfan19 Jun 15 '18 at 15:31
  • "How good is whites compensation" is the question. It may be the best move in the position but is White worse/ better and why? The previous move aren't relevant to the question either. – Ywapom Jun 15 '18 at 15:33
  • Ah but you brought up previous moves, saying that white could have avoided all this if he wanted. And indeed, he could've played this better. I just answered the question about the specific move and you don't seem to like it. Fair enough. – Hockeyfan19 Jun 15 '18 at 15:37