Answers.Body: <p>As <a href="https://www.washingtonpost.com/wp-srv/tech/analysis/kasparov/kasparov.htm" rel="nofollow noreferrer">this Washington Post article</a> explains, Kasparov was not in good shape psychologically. After losing the second game, he got the idea IBM might be cheating and did not recover.</p>
  <p>However, this is not the reason why he resigned. In fact, the game is lost. White has clear advantage. There is an <a href="https://en.chessbase.com/post/25-years-ago-deep-blue-beats-kasparov" rel="nofollow noreferrer">analysis of the game on Chessbase</a> (for some reason partly in English, partly in German) by John Nunn, who provides the following continuation:</p>
  <pre><code>[Date &quot;1997.05.11&quot;]
  [Round &quot;6&quot;]
  [White &quot;Deep Blue&quot;]
  [Black &quot;Kasparov&quot;]
  [FEN &quot;r1k4r/p2nb1p1/2b4p/1p1n1p2/2PP4/3Q1NB1/1P3PPP/R5K1 b - c3 0 19&quot;]
  
  1...bxc4 ( 1...Nb4 2.Qxf5 bxc4 3.Ne5 ) 2.Qxc4 Nb4 3.Re1 Re8 4.Nh4 
  Nb6 5.Qf7 N6d5 6.Nxf5 Kd8 7.Nxg7
  </code></pre>
  <p>He ends his commentary with the words: &quot;A disaster for Kasparov.&quot;</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-06-07T21:05:42.940Z
Answers.LastActivityDate: 2022-06-07T21:05:42.940Z
Answers.UserDisplayName: lodebari
Body: <p>The game is justifiably famous and is linked <a href="https://www.chessgames.com/perl/chessgame?gid=1070917" rel="nofollow noreferrer">here</a>.</p>
  <pre><code>[Date &quot;1997.05.11&quot;]
  [Round &quot;6&quot;]
  [White &quot;Deep Blue&quot;]
  [Black &quot;Kasparov&quot;]
  [FEN &quot;&quot;]
  [startply &quot;39&quot;]
  
  1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nd7 5.Ng5 Ngf6 6.Bd3 e6 7.N1f3 h6 8.Nxe6 Qe7 9.O-O fxe6 10.Bg6+ Kd8 11.Bf4 b5 12.a4 Bb7 13.Re1 Nd5 14.Bg3 Kc8 15.axb5 cxb5 16.Qd3 Bc6 17.Bf5 exf5 18.Rxe7 Bxe7 19.c4 1-0 
  </code></pre>
  <p>It was a shocking upset at the time because <code>19. c4</code> looks completely harmless in this position.</p>
  <p>Analyses after the match and around the time predicted the position would be roughly even for several iterations; Kasparov could have held out. Kasparov had battled Deep Blue at least eleven times prior to this match (six times in 1996 and five uptil then in 1997) and had managed to win convincingly against it, albeit with some losses - but this had not deterred him before.</p>
  <p>Which is why it is all the more surprising Kasparov gave up at this exact point in the game.</p>
  <p>What was going on in Kasparov's head that made him decide he could not possibly continue after c4? Was it simply the idea that Deep Blue must be cheating? Was it some set of lines that made him quail? Were other events around the day eating at him?</p>
  <p>I'm completely mystified by this decision, and would love to have some answers!</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-13T19:14:38.873Z
Comments.Text: Kasparov has admitted that he was perfectly aware that the line he played was bad if white plays the sacrifice, but he didn't think the computer would realize that the sacrifice on e6 is a strong move. So he was completely rattled when the computer surprised him by playing the strongest move in the position. After c4, the queenside opens, and even if there's no immediate checkmate, it's clear that black's king is doomed. There's no real point in continuing this when the opponent is strong enough.
Comments.UserDisplayName: Scounged
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-13T21:17:53.637Z
Comments.Text: @Scounged do you have a source for *Kasparov has admitted that he was perfectly aware that the line he played was bad if white plays the sacrifice, but he didn't think the computer would realize that the sacrifice on e6 is a strong move*? I'm under the impression he accidentally entered that line.
Comments.UserDisplayName: Allure
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-14T02:02:00.457Z
Comments.Text: @Allure Apparently, he mentions it in his book "Deep Thinking", but I don't think this is where I heard of this initially. If you look through the discussion in the game link provided in this question you will find some more detail; apparently Garry was unaware that the Deep Blue team had included that particular opening line into Deep Blue's opening book, and thought it was sure to work out. And then when Nxe6 came on the board he just started shaking his head in disbelief. Although, this could just be something that Garry is saying because he wants to "save face" for some reason.
Comments.UserDisplayName: Scounged
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-14T13:15:06.777Z
Comments.Text: Stockfish/Lichess +3 to 4. I tested a few defenses, but Blacks forces are scattered and everything unravels. (Amusingly, Nxe6 is only +0.2, but has 72% White wins...The advantage value goes up rapid during the game, though. Kc8 seems to be the worst idea.)
Comments.UserDisplayName: Hauke Reddmann
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Comments.CreationDate: 2021-05-14T15:35:20.090Z
Comments.Text: @Scounged, "apparently Garry was unaware that the Deep Blue team had included that particular opening line into Deep Blue's opening book", I thought IBM team claimed that Deep Blue found the move on its own, but it's been a while, I might be misremembering.
Comments.UserDisplayName: Akavall
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-14T16:01:58.723Z
Comments.Text: @Akavall Yeah, I think the Deep Blue team claimed that it found it on its own, but that this claim has been disputed. The details surrounding that match are not entirely clear to me, I'm not sure I trust either Garry or IBM to give a completely fair account of what was going on.
Comments.UserDisplayName: Scounged
Tags: <computer-chess><famous-games><resigning><kasparov>
Title: Why did Kasparov resign at 19. c4 in game 6 of the 1997 Deep Blue match?
ThreadText: # Why did Kasparov resign at 19. c4 in game 6 of the 1997 Deep Blue match?
  
  (Asked by: username_0 on 2021-05-13)
  
  The game is justifiably famous and is linked [here](https://www.chessgames.com/perl/chessgame?gid=1070917).
  
  ```
  [Date "1997.05.11"]
  [Round "6"]
  [White "Deep Blue"]
  [Black "Kasparov"]
  [FEN ""]
  [startply "39"]
  
  1.e4 c6 2.d4 d5 3.Nc3 dxe4 4.Nxe4 Nd7 5.Ng5 Ngf6 6.Bd3 e6 7.N1f3 h6 8.Nxe6 Qe7 9.O-O fxe6 10.Bg6+ Kd8 11.Bf4 b5 12.a4 Bb7 13.Re1 Nd5 14.Bg3 Kc8 15.axb5 cxb5 16.Qd3 Bc6 17.Bf5 exf5 18.Rxe7 Bxe7 19.c4 1-0 
  
  ```
  
  It was a shocking upset at the time because `19. c4` looks completely harmless in this position.
  
  Analyses after the match and around the time predicted the position would be roughly even for several iterations; Kasparov could have held out. Kasparov had battled Deep Blue at least eleven times prior to this match (six times in 1996 and five uptil then in 1997) and had managed to win convincingly against it, albeit with some losses - but this had not deterred him before.
  
  Which is why it is all the more surprising Kasparov gave up at this exact point in the game.
  
  What was going on in Kasparov's head that made him decide he could not possibly continue after c4? Was it simply the idea that Deep Blue must be cheating? Was it some set of lines that made him quail? Were other events around the day eating at him?
  
  I'm completely mystified by this decision, and would love to have some answers!
  
  **Tags:** computer-chess, famous-games, resigning, kasparov
  
  > **Comments:**
  > **username_1**: Kasparov has admitted that he was perfectly aware that the line he played was bad if white plays the sacrifice, but he didn't think the computer would realize that the sacrifice on e6 is a strong move. So he was completely rattled when the computer surprised him by playing the strongest move in the position. After c4, the queenside opens, and even if there's no immediate checkmate, it's clear that black's king is doomed. There's no real point in continuing this when the opponent is strong enough.  
  > **username_2**: @username_1 do you have a source for *Kasparov has admitted that he was perfectly aware that the line he played was bad if white plays the sacrifice, but he didn't think the computer would realize that the sacrifice on e6 is a strong move*? I'm under the impression he accidentally entered that line.  
  > **username_1**: @username_2 Apparently, he mentions it in his book "Deep Thinking", but I don't think this is where I heard of this initially. If you look through the discussion in the game link provided in this question you will find some more detail; apparently Garry was unaware that the Deep Blue team had included that particular opening line into Deep Blue's opening book, and thought it was sure to work out. And then when Nxe6 came on the board he just started shaking his head in disbelief. Although, this could just be something that Garry is saying because he wants to "save face" for some reason.  
  > **username_3**: Stockfish/Lichess +3 to 4. I tested a few defenses, but Blacks forces are scattered and everything unravels. (Amusingly, Nxe6 is only +0.2, but has 72% White wins...The advantage value goes up rapid during the game, though. Kc8 seems to be the worst idea.)  
  > **username_4**: @username_1, "apparently Garry was unaware that the Deep Blue team had included that particular opening line into Deep Blue's opening book", I thought IBM team claimed that Deep Blue found the move on its own, but it's been a while, I might be misremembering.  
  > **username_1**: @username_4 Yeah, I think the Deep Blue team claimed that it found it on its own, but that this claim has been disputed. The details surrounding that match are not entirely clear to me, I'm not sure I trust either Garry or IBM to give a completely fair account of what was going on.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_5 on 2022-06-07. Score: 4 | Accepted answer
  
  As [this Washington Post article](https://www.washingtonpost.com/wp-srv/tech/analysis/kasparov/kasparov.htm) explains, Kasparov was not in good shape psychologically. After losing the second game, he got the idea IBM might be cheating and did not recover.
  
  However, this is not the reason why he resigned. In fact, the game is lost. White has clear advantage. There is an [analysis of the game on Chessbase](https://en.chessbase.com/post/25-years-ago-deep-blue-beats-kasparov) (for some reason partly in English, partly in German) by John Nunn, who provides the following continuation:
  
  ```
  [Date "1997.05.11"]
  [Round "6"]
  [White "Deep Blue"]
  [Black "Kasparov"]
  [FEN "r1k4r/p2nb1p1/2b4p/1p1n1p2/2PP4/3Q1NB1/1P3PPP/R5K1 b - c3 0 19"]
  
  1...bxc4 ( 1...Nb4 2.Qxf5 bxc4 3.Ne5 ) 2.Qxc4 Nb4 3.Re1 Re8 4.Nh4 
  Nb6 5.Qf7 N6d5 6.Nxf5 Kd8 7.Nxg7
  
  ```
  
  He ends his commentary with the words: "A disaster for Kasparov."
  
  
  ---
  
  