Answers.Body: <p>This position is close enough to the beginning of the game that
  the grandmaster may have already analyzed it at home.</p>
  
  <p>Even at the board it is reasonable to analyze the forcing sequence
  12 b4 Bxb4 13 axb4 Qxb4 14 Rfb1 Qe7 (Qd6? 15 Bg3) 15 Qc6 Rb8 16 Rxa7.
  Now we can pause to evaluate. White has recovered one of the sacrificed 
  pawns and has a very active position, while Black hardly has
  a reasonable move: both Knights are pinned to the Queen, and
  any move by Rb8 or Bc8 drops material.  White threatens 17 Bg3,
  attacking the trapped rook, which Black can't free with b5 because
  after 17 Bg3 Rb6? White can play 18 Qxb6 anyway.  If 16 . . . Ne5
  White at least has 17 dxe5 Qxa7 18 exf6 winning two pieces for the Rook.</p>
  
  <p>(I'm analyzing this from the diagram, and may well have missed something.
  But I'm no grandmaster, and never got as high as 2300 USCF before I played
  tournament chess 25+ years ago.  So for an actual grandmaster
  this kind of analysis should be routine once the GM had made the 
  leap of imagination to consider 12 b4!)</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-17T07:01:39.040Z
Answers.Text: +1. The answer to *"And how can he forsee so far in the future?"* is : "That's really not that far!
Answers.UserDisplayName: Evargalo
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-15T18:49:42.427Z
Answers.LastActivityDate: 2018-08-15T18:49:42.427Z
Answers.UserDisplayName: Noam D. Elkies
Answers.Body: <p>If you take the bishop by pawn or queen -- you'll get an equal position with approximately even chances.</p>
  
  <p>After <code>b4</code>, and exchanging pawns for a bishop, there's a good attack on queen side, with <code>Rfb1</code>, then black queen has to find the safe place, and <code>Qc6</code> with quite good chances to win a piece.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-15T16:07:34.393Z
Answers.LastActivityDate: 2018-08-15T17:00:53.723Z
Answers.LastEditDate: 2018-08-15T17:00:53.723Z
Answers.UserDisplayName: lenik
Answers.Body: <p>It's actually a very nice idea. The point is that after:</p>
  
  <p>12.b4 Bxb4 13.axb4 Qxb4 14.Qc6!, White is getting plenty of queenside activity, and is going to win the a7-pawn since Black's rook will have to move to b8. White will still be down a pawn, but will have tremendous queenside activity.</p>
  
  <p>So the point of 12.b4 is that it allows White's queen access to the c6-square, while still winning Black's bishop.</p>
  
  <p>Note that after 12.b4, Black must play 12...Bxb4, or else he just loses his queen since it's trapped.</p>
  
  <p>As for how the GM could have foreseen this, it takes a combination of natural talent and countless hours of practicing calculation to ingrain patterns into the mind. Although I wouldn't say this combination is close to GM calibre, maybe 2200 level at best.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-18T05:08:30.093Z
Answers.LastActivityDate: 2018-08-18T05:08:30.093Z
Answers.UserDisplayName: Inertial Ignorance
Answers.Body: <p>I assume the last move was b2-b4.  The idea is 1...Bxb4 2.Rfb1 threatening to trap the queen with axb4.  So Bishop somewhere (2...Be7).  Now can we trap that queen or something? 3.Rb5 queen a6 is only open square which allows Rook discovery...but I don't see a win here. hmmm, 4.Rc5 Qb7 (4...b5!?) 5.Rc7 Qb8 6.Bg3!?</p>
  
  <blockquote>
    <p>Okay this line is total junk as pointed out in comments and the answer
    is far simpler.  Black has problems with the unprotected Rook on a8
    and it can't find a home on b8 because Bg3.</p>
  </blockquote>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-15T16:31:02.820Z
Answers.Text: Stockfish evaluates the position as **+3** after **1. .. Bxb4**, but **-2.7** after **2. Rfb1**. After **2 .. Be7 3. Rb5 Qa6 4. Rc5 Qxd3 5. Qxd3 bxc5**, white is down to **-4.5**.
Answers.UserDisplayName: Dennis
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-15T16:39:16.357Z
Answers.Text: @Dennis Nice, I guess I am rusty,  so what did the GM see 2.Qc6 maybe.
Answers.UserDisplayName: Ywapom
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-15T16:43:35.600Z
Answers.Text: Still according to Stockfish, the best continuation is **2. axb4 Qxb4 3. Rfb1 Qe7 4. Qc6**, as suggested by lenik.
Answers.UserDisplayName: Dennis
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Answers.CreationDate: 2018-08-15T16:12:29.230Z
Answers.LastActivityDate: 2018-08-15T16:48:51.500Z
Answers.LastEditDate: 2018-08-15T16:48:51.500Z
Answers.UserDisplayName: Ywapom
Body: <p><a href="https://i.sstatic.net/Qw390.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Qw390.png" alt="enter image description here"></a></p>
  
  <p>Why is 12. b4 played by a GM? Why doesn't he just capture the bishop? And how can he forsee so far in the future? Am I missing something?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-08-17T07:03:06.267Z
Comments.Text: Looks like a great game. Can you tell us who the players are and what is the venue ?
Comments.UserDisplayName: Evargalo
Tags: <analysis>
Title: How can a human figure out best move in this position?
ThreadText: # How can a human figure out best move in this position?
  
  (Asked by: username_0 on 2018-08-15)
  
  [![enter image description here](https://i.sstatic.net/Qw390.png)](https://i.sstatic.net/Qw390.png)
  
  Why is 12. b4 played by a GM? Why doesn't he just capture the bishop? And how can he forsee so far in the future? Am I missing something?
  
  **Tags:** analysis
  
  > **Comments:**
  > **username_1**: Looks like a great game. Can you tell us who the players are and what is the venue ?  
  
  ---
  
  ## 4 answers
  
  ### Answer by username_2 on 2018-08-15. Score: 5
  
  This position is close enough to the beginning of the game that
  the grandmaster may have already analyzed it at home.
  
  Even at the board it is reasonable to analyze the forcing sequence
  12 b4 Bxb4 13 axb4 Qxb4 14 Rfb1 Qe7 (Qd6? 15 Bg3) 15 Qc6 Rb8 16 Rxa7.
  Now we can pause to evaluate. White has recovered one of the sacrificed
  pawns and has a very active position, while Black hardly has
  a reasonable move: both Knights are pinned to the Queen, and
  any move by Rb8 or Bc8 drops material. White threatens 17 Bg3,
  attacking the trapped rook, which Black can't free with b5 because
  after 17 Bg3 Rb6? White can play 18 Qxb6 anyway. If 16 . . . Ne5
  White at least has 17 dxe5 Qxa7 18 exf6 winning two pieces for the Rook.
  
  (I'm analyzing this from the diagram, and may well have missed something.
  But I'm no grandmaster, and never got as high as 2300 USCF before I played
  tournament chess 25+ years ago. So for an actual grandmaster
  this kind of analysis should be routine once the GM had made the
  leap of imagination to consider 12 b4!)
  
  > **Comments:**
  > **username_1**: +1. The answer to *"And how can he forsee so far in the future?"* is : "That's really not that far!  
  
  ---
  
  ### Answer by username_3 on 2018-08-15. Score: 2
  
  If you take the bishop by pawn or queen -- you'll get an equal position with approximately even chances.
  
  After `b4`, and exchanging pawns for a bishop, there's a good attack on queen side, with `Rfb1`, then black queen has to find the safe place, and `Qc6` with quite good chances to win a piece.
  
  
  ---
  
  ### Answer by username_4 on 2018-08-18. Score: 1
  
  It's actually a very nice idea. The point is that after:
  
  12.b4 Bxb4 13.axb4 Qxb4 14.Qc6!, White is getting plenty of queenside activity, and is going to win the a7-pawn since Black's rook will have to move to b8. White will still be down a pawn, but will have tremendous queenside activity.
  
  So the point of 12.b4 is that it allows White's queen access to the c6-square, while still winning Black's bishop.
  
  Note that after 12.b4, Black must play 12...Bxb4, or else he just loses his queen since it's trapped.
  
  As for how the GM could have foreseen this, it takes a combination of natural talent and countless hours of practicing calculation to ingrain patterns into the mind. Although I wouldn't say this combination is close to GM calibre, maybe 2200 level at best.
  
  
  ---
  
  ### Answer by username_5 on 2018-08-15. Score: -1
  
  I assume the last move was b2-b4. The idea is 1...Bxb4 2.Rfb1 threatening to trap the queen with axb4. So Bishop somewhere (2...Be7). Now can we trap that queen or something? 3.Rb5 queen a6 is only open square which allows Rook discovery...but I don't see a win here. hmmm, 4.Rc5 Qb7 (4...b5!?) 5.Rc7 Qb8 6.Bg3!?
  
  > Okay this line is total junk as pointed out in comments and the answer
  > is far simpler. Black has problems with the unprotected Rook on a8
  > and it can't find a home on b8 because Bg3.
  
  > **Comments:**
  > **username_6**: Stockfish evaluates the position as **+3** after **1. .. Bxb4**, but **-2.7** after **2. Rfb1**. After **2 .. Be7 3. Rb5 Qa6 4. Rc5 Qxd3 5. Qxd3 bxc5**, white is down to **-4.5**.  
  > **username_5**: @username_6 Nice, I guess I am rusty,  so what did the GM see 2.Qc6 maybe.  
  > **username_6**: Still according to Stockfish, the best continuation is **2. axb4 Qxb4 3. Rfb1 Qe7 4. Qc6**, as suggested by username_3.  
  
  ---
  
  