Answers.Body: <p>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 </p>
  
  <p>21.Nd4 [21.Nc3 is quite the same] Bxd4 22.Bxd4 Rxb5 and Black should win.</p>
  
  <p>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.</p>
  
  <p>Probably White would have reached a much better version of the game with 18.Nd4!? instead of 18.Rc1.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-06-15T15:34:34.983Z
Answers.Text: It was my feeling that White is a tempo short as well.
Answers.UserDisplayName: Ywapom
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Answers.CreationDate: 2018-06-15T15:46:51.770Z
Answers.Text: 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.
Answers.UserDisplayName: Ywapom
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Answers.CreationDate: 2018-06-15T09:32:08.317Z
Answers.LastActivityDate: 2018-06-15T15:40:21.450Z
Answers.LastEditDate: 2018-06-15T15:40:21.450Z
Answers.UserDisplayName: Evargalo
Answers.Body: <p>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.</p>
  
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Answers.CreationDate: 2018-06-15T15:28:23.593Z
Answers.Text: 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.
Answers.UserDisplayName: Hockeyfan19
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Answers.CreationDate: 2018-06-15T15:31:21.780Z
Answers.Text: In particular white is overall worse in this line. He has some play but black is certainly better.
Answers.UserDisplayName: Hockeyfan19
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Answers.CreationDate: 2018-06-15T15:33:42.257Z
Answers.Text: "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.
Answers.UserDisplayName: Ywapom
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Answers.CreationDate: 2018-06-15T15:37:02.603Z
Answers.Text: 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.
Answers.UserDisplayName: Hockeyfan19
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Answers.CreationDate: 2018-06-15T02:31:49.133Z
Answers.LastActivityDate: 2018-06-15T02:31:49.133Z
Answers.UserDisplayName: Hockeyfan19
Body: <p>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.</p>
  
  <pre><code>[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
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-14T17:34:17.703Z
Comments.Text: 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.
Comments.UserDisplayName: hoacin
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-14T20:42:24.727Z
Comments.Text: 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.
Comments.UserDisplayName: Philip Roe
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-14T20:46:22.627Z
Comments.Text: @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.
Comments.UserDisplayName: Ywapom
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-15T12:54:06.650Z
Comments.Text: Your pgn is a bit unclear, for example 11... Nxd4 when nothing had moved to d4, or 13.. Ne2 should be Nxe2
Comments.UserDisplayName: Hockeyfan19
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-15T16:16:46.930Z
Comments.Text: @Hockeyfan19 That was my bad, when fixing the original pgn to get the board to display. I've corrected it.
Comments.UserDisplayName: Herb
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-15T16:21:47.127Z
Comments.Text: Much better, though black move 13 should also be nx I think.
Comments.UserDisplayName: Hockeyfan19
Tags: <english-opening>
Title: English opening exchange-sacrifice compensation
ThreadText: # English opening exchange-sacrifice compensation
  
  (Asked by: username_0 on 2018-06-14)
  
  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
  
  **Tags:** english-opening
  
  > **Comments:**
  > **username_1**: 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.  
  > **username_2**: 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.  
  > **username_0**: @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.  
  > **username_3**: Your pgn is a bit unclear, for example 11... Nxd4 when nothing had moved to d4, or 13.. Ne2 should be Nxe2  
  > **username_4**: @username_3 That was my bad, when fixing the original pgn to get the board to display. I've corrected it.  
  > **username_3**: Much better, though black move 13 should also be nx I think.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_5 on 2018-06-15. Score: 2 | Accepted answer
  
  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.
  
  > **Comments:**
  > **username_0**: It was my feeling that White is a tempo short as well.  
  > **username_0**: 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.  
  
  ---
  
  ### Answer by username_3 on 2018-06-15. Score: -1
  
  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.
  
  > **Comments:**
  > **username_3**: 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.  
  > **username_3**: In particular white is overall worse in this line. He has some play but black is certainly better.  
  > **username_0**: "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.  
  > **username_3**: 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.  
  
  ---
  
  