Answers.Body: <p><code>1. a4</code> allows White to place his knight on the c4-square without having to worry about <code>...b5</code> kicking it away because that would be too weakening for Black, because it would make the a-pawn backwards on an open file.</p>
  
  <p><code>1. a4</code> also gains space and opens the possibility of <code>a5-a6</code> to soften the Black queenside for the g2-bishop. If black stops this with <code>...a6</code> or <code>...a5</code>, then Black will have a hole on b6.</p>
  
  <p>A knight on c4 would allow white to move his bishop to f4 to attack the black queen. If Black responds <code>...e5</code>, this creates a permanent weakness on d6, and White can put his knight there. <code>...e5</code> also blocks Black's bishop. The knight on c4 also takes away many squares from the black queen, so if Black does not want to weaken with ...e5, the black queen will have to go to an inactive square.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-12-29T22:13:37.223Z
Answers.Text: Also, none of the plans you mention for White involve obstructing the open h3-f3 rank, so a4 makes a quick(er) development of the R via h3, another possible plus.
Answers.UserDisplayName: Jeff Y
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-12-31T01:13:55.617Z
Answers.Text: via a3, you mean.  Note too that neither of the potential weaknesses of a4 exists here: Black is in no position to mount an attack on a4, and can't quickly occupy b4 with a Knight (the route f6-d5-b4 runs into e4xd5, and even if Black takes the time for Nd7-b8-a6-b4 White can comfortably eject the steed with c3).
Answers.UserDisplayName: Noam D. Elkies
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Answers.CreationDate: 2020-01-12T23:36:36.000Z
Answers.Text: With the game continuing 13. Nb3, this would seem incorrect, since White never places his knight on c4.
Answers.UserDisplayName: Allure
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Answers.CreationDate: 2015-12-29T17:58:04.820Z
Answers.LastActivityDate: 2015-12-29T17:58:04.820Z
Answers.UserDisplayName: limits
Body: <p><a href="https://i.sstatic.net/GB1Qr.jpg" rel="noreferrer"><img src="https://i.sstatic.net/GB1Qr.jpg" alt="enter image description here"></a></p>
  
  <p>This is a position from a game between Fischer and Ibrahimglu, 1970.</p>
  
  <p>Black's last move was 11. ... Qc7 from d8. According to Stockfish (depth = 28), 12. a4 is the best move for White. The other recommended moves are Nb3 and Rd1. But a4 seems to be better than Nb3 by more than 0.1 point.</p>
  
  <p>It seems to be a very logical move as Fischer played it too. Only the logic behind it is out of my (an intermediate player) reach. :)</p>
  
  <p>The game continued with 12. ... Rad8 13. Nb3 b6 14. Be3 c5... Fischer went on winning this game.</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T05:35:05.217Z
Comments.Text: A score difference of .1 is surely 'within the noise'. That is, I am not sure any two moves with scores different by .1 are really any different, qualitatively.
Comments.UserDisplayName: Tony Ennis
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T06:24:57.630Z
Comments.Text: Yes... the difference is small... but still a4 seems to be a good move at this position, but I would not have considered it here.
Comments.UserDisplayName: Srijannath
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T08:16:04.817Z
Comments.Text: Why it's out of reach? a4 is just a standard idea, pushing for queenside spacing and preparing to meet ...Nb6 with a5. The move may also lead to an open a-file for the rook. Very typical idea.
Comments.UserDisplayName: SmallChess
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T16:10:14.250Z
Comments.Text: I would have been looking at `Nb3` followed by developing the black bishop.  `a4` never would have occurred to me.
Comments.UserDisplayName: Tony Ennis
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T17:59:16.990Z
Comments.Text: b3 is actually an ineffective square for the knight.
Comments.UserDisplayName: limits
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T21:23:14.743Z
Comments.Text: a2-a4 then Nc4 looks quite logical. c4 is obviously good for knight. And a4 makes c4 square more stable. Also gains space. Maybe leads to an open a-file. I would play a4 too.
Comments.UserDisplayName: ferit
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-12-29T21:44:25.387Z
Comments.Text: Depth 28 is not very deep at all.  I play engines on correspondence on FICGS and regularly let my engines go to depth 40 give or take.
Comments.UserDisplayName: Dexygen
Tags: <strategy>
Title: Why is, according to Stockfish (depth = 28), a4 the best move here for White?
ThreadText: # Why is, according to Stockfish (depth = 28), a4 the best move here for White?
  
  (Asked by: username_0 on 2015-12-29)
  
  [![enter image description here](https://i.sstatic.net/GB1Qr.jpg)](https://i.sstatic.net/GB1Qr.jpg)
  
  This is a position from a game between Fischer and Ibrahimglu, 1970.
  
  Black's last move was 11. ... Qc7 from d8. According to Stockfish (depth = 28), 12. a4 is the best move for White. The other recommended moves are Nb3 and Rd1. But a4 seems to be better than Nb3 by more than 0.1 point.
  
  It seems to be a very logical move as Fischer played it too. Only the logic behind it is out of my (an intermediate player) reach. :)
  
  The game continued with 12. ... Rad8 13. Nb3 b6 14. Be3 c5... Fischer went on winning this game.
  
  **Tags:** strategy
  
  > **Comments:**
  > **username_1**: A score difference of .1 is surely 'within the noise'. That is, I am not sure any two moves with scores different by .1 are really any different, qualitatively.  
  > **username_0**: Yes... the difference is small... but still a4 seems to be a good move at this position, but I would not have considered it here.  
  > **username_2**: Why it's out of reach? a4 is just a standard idea, pushing for queenside spacing and preparing to meet ...Nb6 with a5. The move may also lead to an open a-file for the rook. Very typical idea.  
  > **username_1**: I would have been looking at `Nb3` followed by developing the black bishop.  `a4` never would have occurred to me.  
  > **username_3**: b3 is actually an ineffective square for the knight.  
  > **username_4**: a2-a4 then Nc4 looks quite logical. c4 is obviously good for knight. And a4 makes c4 square more stable. Also gains space. Maybe leads to an open a-file. I would play a4 too.  
  > **username_5**: Depth 28 is not very deep at all.  I play engines on correspondence on FICGS and regularly let my engines go to depth 40 give or take.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_3 on 2015-12-29. Score: 6
  
  `1. a4` allows White to place his knight on the c4-square without having to worry about `...b5` kicking it away because that would be too weakening for Black, because it would make the a-pawn backwards on an open file.
  
  `1. a4` also gains space and opens the possibility of `a5-a6` to soften the Black queenside for the g2-bishop. If black stops this with `...a6` or `...a5`, then Black will have a hole on b6.
  
  A knight on c4 would allow white to move his bishop to f4 to attack the black queen. If Black responds `...e5`, this creates a permanent weakness on d6, and White can put his knight there. `...e5` also blocks Black's bishop. The knight on c4 also takes away many squares from the black queen, so if Black does not want to weaken with ...e5, the black queen will have to go to an inactive square.
  
  > **Comments:**
  > **username_6**: Also, none of the plans you mention for White involve obstructing the open h3-f3 rank, so a4 makes a quick(er) development of the R via h3, another possible plus.  
  > **username_7**: via a3, you mean.  Note too that neither of the potential weaknesses of a4 exists here: Black is in no position to mount an attack on a4, and can't quickly occupy b4 with a Knight (the route f6-d5-b4 runs into e4xd5, and even if Black takes the time for Nd7-b8-a6-b4 White can comfortably eject the steed with c3).  
  > **username_8**: With the game continuing 13. Nb3, this would seem incorrect, since White never places his knight on c4.  
  
  ---
  
  