Answers.Body: <p>Assuming you are talking about <a href="http://www.chessgames.com/perl/chessgame?gid=1848607" rel="nofollow noreferrer">this game</a>.</p>
  
  <p><strong>Short answer</strong> </p>
  
  <p>Carlsen probably <em>calculated</em> the sacrifice only a few moves before actually playing it, when he was pondering over 46.Rc1 or 47.Qxf4. However, he must have had the pattern with Qh6+ in a corner of his mind for much longer.</p>
  
  <p><strong>Detailed answer</strong></p>
  
  <p>Since Carlsen's position looked winning for a while, at least since the operation starting from 31.Bxd7 and ending with 37.Nxb3, he did not have to be calculating his own attacking possibilities very far ahead: his main goal during that phase (moves 38-46) was to consolidate his material advantage.</p>
  
  <p>I think he calculated the variation that occured in the game until the end before grabbing the pawn with 47.Qxf4. Since allowing both Black's major pieces on his second rank looks risky, that's when he needed to be back up his choices with precise calculation. Moreover, he played the moves afterwards pretty fast. Of course, the calculation itself is very simple for players of that level.</p>
  
  <p>On the other hand, it is very possible that he had the pattern Qh6+! in a corner of his mind for at least ten moves. With Rf5 and Ph5 on the board, and black having a weak back rank, Carlsen's pattern recognition must have scanned the kingside for possible mating ideas, and spotted a long time ago that a check on h6 would be decisive.</p>
  
  <p>As far as computers are concerned, they can find the mating line in a few milliseconds if you feed them the position after 46...Ra7, and they will confidently grab the f4-pawn and give a question mark to 48...Qf2. Before move 46, play doesn't have a forced character at all, so they cannot predict what will appear on the board, but their trees of variations must be full of mates starting from Rc8+ and Qh6 anytime the 8-th rank and the c1-h6 diagonal are cleared.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-14T07:23:26.960Z
Answers.LastActivityDate: 2017-09-14T16:02:27.853Z
Answers.LastEditDate: 2017-09-14T16:02:27.853Z
Answers.UserDisplayName: Evargalo
Body: <p>How many moves ahead did Carlsen see his Queen sacrifice in the final game, and how many moves ahead did the strongest chess program spot it?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-14T00:45:49.817Z
Comments.Text: Do you mean the queen sacrifice he did to Karjakin in the final blitz game in WCC 2016?
Comments.UserDisplayName: SmallChess
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-14T00:46:42.217Z
Comments.Text: All modern engines can spot that like instantly. It was a simple tactic for the computers.
Comments.UserDisplayName: SmallChess
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-14T07:02:44.147Z
Comments.Text: 1. You should add context to precise this is the final Carlsen-Karjakin rapid game you are referring to, and clear any ambiguity. 2. SmallChess: I think the question is when did Carlsen find the queen sacrifice, before the position appeared on the board.
Comments.UserDisplayName: Evargalo
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-14T07:16:22.237Z
Comments.Text: @OlivierPucher only Carlsen himself can answer that.
Comments.UserDisplayName: SmallChess
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-14T07:24:32.970Z
Comments.Text: @SmallChess: if he can, which is not obvious either...
Comments.UserDisplayName: Evargalo
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-14T14:46:24.850Z
Comments.Text: "How many moves ahead did Carlsen see his Queen sacrifice in the final game?" This is something only Carlsen knows. You are asking us to speculate and give our opinions. Voting to close.
Comments.UserDisplayName: Brian Towers
Tags: <strategy>
Title: What was the lookahead capability for Carlsen's Queen sacrifice?
ThreadText: # What was the lookahead capability for Carlsen's Queen sacrifice?
  
  (Asked by: username_0 on 2017-09-14)
  
  How many moves ahead did Carlsen see his Queen sacrifice in the final game, and how many moves ahead did the strongest chess program spot it?
  
  **Tags:** strategy
  
  > **Comments:**
  > **username_1**: Do you mean the queen sacrifice he did to Karjakin in the final blitz game in WCC 2016?  
  > **username_1**: All modern engines can spot that like instantly. It was a simple tactic for the computers.  
  > **username_2**: 1. You should add context to precise this is the final Carlsen-Karjakin rapid game you are referring to, and clear any ambiguity. 2. username_1: I think the question is when did Carlsen find the queen sacrifice, before the position appeared on the board.  
  > **username_1**: @OlivierPucher only Carlsen himself can answer that.  
  > **username_2**: @username_1: if he can, which is not obvious either...  
  > **username_3**: "How many moves ahead did Carlsen see his Queen sacrifice in the final game?" This is something only Carlsen knows. You are asking us to speculate and give our opinions. Voting to close.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_2 on 2017-09-14. Score: 5
  
  Assuming you are talking about [this game](http://www.chessgames.com/perl/chessgame?gid=1848607).
  
  **Short answer**
  
  Carlsen probably *calculated* the sacrifice only a few moves before actually playing it, when he was pondering over 46.Rc1 or 47.Qxf4. However, he must have had the pattern with Qh6+ in a corner of his mind for much longer.
  
  **Detailed answer**
  
  Since Carlsen's position looked winning for a while, at least since the operation starting from 31.Bxd7 and ending with 37.Nxb3, he did not have to be calculating his own attacking possibilities very far ahead: his main goal during that phase (moves 38-46) was to consolidate his material advantage.
  
  I think he calculated the variation that occured in the game until the end before grabbing the pawn with 47.Qxf4. Since allowing both Black's major pieces on his second rank looks risky, that's when he needed to be back up his choices with precise calculation. Moreover, he played the moves afterwards pretty fast. Of course, the calculation itself is very simple for players of that level.
  
  On the other hand, it is very possible that he had the pattern Qh6+! in a corner of his mind for at least ten moves. With Rf5 and Ph5 on the board, and black having a weak back rank, Carlsen's pattern recognition must have scanned the kingside for possible mating ideas, and spotted a long time ago that a check on h6 would be decisive.
  
  As far as computers are concerned, they can find the mating line in a few milliseconds if you feed them the position after 46...Ra7, and they will confidently grab the f4-pawn and give a question mark to 48...Qf2. Before move 46, play doesn't have a forced character at all, so they cannot predict what will appear on the board, but their trees of variations must be full of mates starting from Rc8+ and Qh6 anytime the 8-th rank and the c1-h6 diagonal are cleared.
  
  
  ---
  
  