Answers.Body: <blockquote>
    <p>If you know others and know yourself, you will not be imperiled in a
    hundred battles; if you do not know others but know yourself, you win
    one and lose one; if you do not know others and do not know yourself,
    you will be imperiled in every single battle. - Sun Tzu</p>
  </blockquote>
  
  <p>Chess is a game with countless variations.  It is commonly known that there are over 9 million possible positions after just three moves.  Nobody is expected to explore all of them, not even the mighty supercomputers.  There <em>will</em> be lines which are simply not fully explored in every game we play.</p>
  
  <p>One of the early algorithms you learn when developing chess computers is min/max.  It's a rather blatantly obvious algorithm when you get down to it: the idea is that both players are trying to maximize their own benefit.  In min/max, we treat this as you trying to maximize your advantage, and they are trying to minimize it.</p>
  
  <p>If you play chess using the kind of thinking behind min/max, you quickly find yourself limited.  No two players are thinking exactly the same.  They value different kinds of positions, different tactics.  You may find that it isn't effective to model your opponent as trying to minimize your advantage.  You have to recognize that they are merely trying to maximize their advantage.  The two phrases, "minimizing your advantage" vs "maximizing their advantage" are closely related in many situations, but they differ greatly in others.  In fact, Chess often hovers in that meddlesome region where the position is so strange that both players are approaching it quite differently.  Nowhere is this more visible than in a gambit.  In a gambit, you offer something in exchange for an advantage that you find more valuable.  They don't have to take it.  However, in many situations they may decide that it is in their interests to accept the gambit.  Min/max cannot explain a gambit; it cannot explain why both players would want the same position for different reasons.</p>
  
  <p>Accordingly, it is essential in Chess to get into the head of your opponent.  Grandmasters may do this for months, studying up on the play styles of their opponents.</p>
  
  <p>An opponent can get into your head at any time.  Kasparaov v. Deep Blue may be the most famous example.  In one game, Deep Blue simply refused to accept an obvious materialistic move and found a more "human" move.  For the rest of the tournament Kasparov was <em>convinced</em> there had to be a human helping Deep Blue out, and that psychologically destroyed him (even though the computer wasn't even aware of a psyche).</p>
  
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Answers.UserDisplayName: Cort Ammon
Answers.Body: <p>You can only adjust your plan to your opponent when you have multiple moves that are equally or almost equally good objectively, since sometimes one of these moves might seem better than the others against a particular opponent. But making an objectively poor move in the hopes that your opponent will not find the refutation is asking for punishment.</p>
  
  <p>By far the primary means of adjusting one's style to one's opponent is selecting the opening. For example, the Sicilian Defense and the French Defense are both good choices objectively, but you might have reason to believe your opponent will perform worse against the Sicilian than the French. But if you know the French better than the Sicilian, you should probably choose the French, or else your choice of opening might hurt you more than your opponent.</p>
  
  <p>This isn't the sort of thing most players really need to worry about until they become quite strong (master level). Usually in a tournament game you should just make the moves you're most comfortable with and play the moves that seem objectively best.</p>
  
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Answers.CreationDate: 2018-05-12T01:01:52.557Z
Answers.Text: It's too bad that this answer comes so late. Hopefully it won't stay buried at the bottom of the answer column! It is the best answer so far.
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-12-09T23:02:09.020Z
Answers.Text: I would stress that for almost anyone looking to improve their ability, it would be better to learn to find objectively stronger moves instead of trying to find weaker moves that might be better against specific opponents. You never know when your opponent will see through your weaker plan and refute it. But against the objectively strongest plan, there is no refutation! This is also very situational. It's rare that you'll know an opponent well enough to find a weaker move that is stronger against them. But sometimes in lost positions, a less optimal but "trickier" move can save the game.
Answers.UserDisplayName: Jordan Rieger
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Answers.UserDisplayName: Kef Schecter
Answers.Body: <p>Let me quote Botvinnik's words from a chess history book in Russian. It is about his preparation for his rematch against Tal after losing the champion's title to him.</p>
  
  <p>I decided to play working in two directions. Firstly, to take a lesson from Tal and become a tactical trickster. Secondly, to prepare openings and middlegame plans with a closed character so that the board is fragmented into separate regions, the pieces are little mobile, even if objectively my positions are worse, hoping that my opponent will not be able to make use of his ingenuity and memory, while my understanding of positions might tell.  </p>
  
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Answers.UserDisplayName: MichalRyszardWojcik
Answers.Body: <p>Botvinnik lost to Smyslov and to Tal in world championship matches and then won with them in rematches. From his writing it follows that he has studied the style of his opponents and learned to play against them. In playing against Tal in the rematch he avoided tactical complications in favor of dry endgames and that supposedly worked out. This is just an idea how to answer your question. One would need to investigate this line more deeply.</p>
  
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Answers.CreationDate: 2016-06-11T18:00:29.687Z
Answers.Text: Why did you wrote 3 different answers. You can merge all into one single answer here.
Answers.UserDisplayName: manav m-n
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Answers.CreationDate: 2016-06-11T18:06:20.523Z
Answers.Text: @manav m-n Each answer is different and can be evaluated and commented separately. These are things which may require a further discussion or improvement. It is actually a benefit that the interface allows multiple answers from the same user.
Answers.UserDisplayName: MichalRyszardWojcik
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Answers.CreationDate: 2016-06-13T10:54:18.613Z
Answers.Text: Actually in the rematch against Tal the main change in Botvinnik's play (according to Tal at least) was that he became more confident, and didn't avoid complications. He tried the going for the endgame strategy in the first match, and it wasn't enough. Actually you quote the same in a later answer from Botvinnik.
Answers.UserDisplayName: Usern4me
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Answers.UserDisplayName: MichalRyszardWojcik
Answers.Body: <p>The world champion Emanuel Lasker is reputed to be a master of psychology, adjusting his play to upset his opponents to the point of making inferior moves on purpose. This is just an idea to pursue in the literature. For example, Kasparov writes about it in his predecessor series.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
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Answers.UserDisplayName: MichalRyszardWojcik
Answers.Body: <p>The young Bobby Fischer used to play the same opening scheme from game to game against every opponent. Later he adopted the element of surprise and varied his openings. I remember reading about it somewhere and it was worded so that the aspect of psychological battle became one of his tools contrary to his previous straightforward play. </p>
  
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Answers.UserDisplayName: MichalRyszardWojcik
Answers.Body: <p>I remember reading about Taimanov's preparation against Fischer before the match which he famously lost 6 to nil. His helpers recommended him to play the French Defense because Fischer was known to be ineffective against it, but Taimanov disregarded this advice and played his favorite Sicilian Defense which was to Fischer's liking.</p>
  
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Answers.UserDisplayName: MichalRyszardWojcik
Answers.Body: <p>I remember reading Carlsen's comments after his first match against Anand to the effect that he soon discovered that he needed no change from his usual play but was prepared to play differently. I don't remember any particulars as to this modified way of playing that he had prepared but at least this answers the question in the positive that this phenomenon is real in preparation against opponents.</p>
  
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Answers.UserDisplayName: MichalRyszardWojcik
Answers.Body: <p>American master Fred Reinfield advised people to "play the man and not the board."</p>
  
  <p>While an opponent will have a given strength, X, s/he probably will not have the same strength in all types of games. It might be a strength of X+100 in positional games and X-100 in tactical games (or vice-versa). </p>
  
  <p>Say your rated strength Y, is X-50. But if your strength is X in tactical games and X-100 in positional games, knowing your opponent's (game) personality may enable you to match your X level of tactical play against his X-100.</p>
  
  <p>Some years ago, I was a 1500 player playing with two 1800 players. The two other players played evenly between themselves. I was "even money" against one of these two players because I was able to match my strength in positional games (relative to my rating) against his weakness in this area. I was a heavy underdog against the other player, who matched me positionally, but had better tactics than me.</p>
  
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Answers.LastEditDate: 2016-07-10T20:44:16.787Z
Answers.UserDisplayName: Tom Au
Body: <p>From <a href="https://meta.stackoverflow.com/questions/325936/reputation-and-badges-should-be-kept-hidden-until-the-question-is-answered">Reputation and badges should be kept hidden until the question is answered</a>, the below assertion is presented:</p>
  
  <p>It is often asked in chess, that does the personality of the opponent player has any influence on their game plan, the answer is almost yes for all grandmasters. Most also feel uncomfortable playing against Computer as a competitor in chess even if it's radically low-rated running at 1/10th of its strength. Why, because people lose, not because that they are weak players but because of the inherent psychology involved that "computers make no mistakes". On the other hand, low-rated players often lose quickly when they know before-hand that the opponent player is a grandmaster. However, if the opponent rating is unknown, he tends to a better play, and even a long shot at winning it.</p>
  
  <p>Do you agree with the above assertion or did you had any contrary experiences in chess. How do grandmasters employ assessing the personality as a tool to develop their game plan?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-05-12T00:58:37.437Z
Comments.Text: Not a master, I have wondered the same thing. In my own games, I have tried several times to adjust my style to opponents' weaknesses. It seems that this *should* work, and I like the idea, but for some reason, such adjustments do not seem to work very well for me. If I want to win, unfortunately, I end up having to play the best moves I can find irrespective of the opponent's weaknesses. It's too bad, really: I have never been able to leverage psychological play very well, despite repeated attempts; so it is interesting to watch the grandmasters do it.
Comments.UserDisplayName: thb
Tags: <opening><strategy><psychology><grandmaster><planning>
Title: Does knowing your opponent's personality have any influence on the game-plan
ThreadText: # Does knowing your opponent's personality have any influence on the game-plan
  
  (Asked by: username_0 on 2016-06-11)
  
  From [Reputation and badges should be kept hidden until the question is answered](https://meta.stackoverflow.com/questions/325936/reputation-and-badges-should-be-kept-hidden-until-the-question-is-answered), the below assertion is presented:
  
  It is often asked in chess, that does the personality of the opponent player has any influence on their game plan, the answer is almost yes for all grandmasters. Most also feel uncomfortable playing against Computer as a competitor in chess even if it's radically low-rated running at 1/10th of its strength. Why, because people lose, not because that they are weak players but because of the inherent psychology involved that "computers make no mistakes". On the other hand, low-rated players often lose quickly when they know before-hand that the opponent player is a grandmaster. However, if the opponent rating is unknown, he tends to a better play, and even a long shot at winning it.
  
  Do you agree with the above assertion or did you had any contrary experiences in chess. How do grandmasters employ assessing the personality as a tool to develop their game plan?
  
  **Tags:** opening, strategy, psychology, grandmaster, planning
  
  > **Comments:**
  > **username_1**: Not a master, I have wondered the same thing. In my own games, I have tried several times to adjust my style to opponents' weaknesses. It seems that this *should* work, and I like the idea, but for some reason, such adjustments do not seem to work very well for me. If I want to win, unfortunately, I end up having to play the best moves I can find irrespective of the opponent's weaknesses. It's too bad, really: I have never been able to leverage psychological play very well, despite repeated attempts; so it is interesting to watch the grandmasters do it.  
  
  ---
  
  ## 9 answers
  
  ### Answer by username_2 on 2016-06-11. Score: 3 | Accepted answer
  
  > If you know others and know yourself, you will not be imperiled in a
  > hundred battles; if you do not know others but know yourself, you win
  > one and lose one; if you do not know others and do not know yourself,
  > you will be imperiled in every single battle. - Sun Tzu
  
  Chess is a game with countless variations. It is commonly known that there are over 9 million possible positions after just three moves. Nobody is expected to explore all of them, not even the mighty supercomputers. There *will* be lines which are simply not fully explored in every game we play.
  
  One of the early algorithms you learn when developing chess computers is min/max. It's a rather blatantly obvious algorithm when you get down to it: the idea is that both players are trying to maximize their own benefit. In min/max, we treat this as you trying to maximize your advantage, and they are trying to minimize it.
  
  If you play chess using the kind of thinking behind min/max, you quickly find yourself limited. No two players are thinking exactly the same. They value different kinds of positions, different tactics. You may find that it isn't effective to model your opponent as trying to minimize your advantage. You have to recognize that they are merely trying to maximize their advantage. The two phrases, "minimizing your advantage" vs "maximizing their advantage" are closely related in many situations, but they differ greatly in others. In fact, Chess often hovers in that meddlesome region where the position is so strange that both players are approaching it quite differently. Nowhere is this more visible than in a gambit. In a gambit, you offer something in exchange for an advantage that you find more valuable. They don't have to take it. However, in many situations they may decide that it is in their interests to accept the gambit. Min/max cannot explain a gambit; it cannot explain why both players would want the same position for different reasons.
  
  Accordingly, it is essential in Chess to get into the head of your opponent. Grandmasters may do this for months, studying up on the play styles of their opponents.
  
  An opponent can get into your head at any time. Kasparaov v. Deep Blue may be the most famous example. In one game, Deep Blue simply refused to accept an obvious materialistic move and found a more "human" move. For the rest of the tournament Kasparov was *convinced* there had to be a human helping Deep Blue out, and that psychologically destroyed him (even though the computer wasn't even aware of a psyche).
  
  
  ---
  
  ### Answer by username_3 on 2018-05-12. Score: 5
  
  You can only adjust your plan to your opponent when you have multiple moves that are equally or almost equally good objectively, since sometimes one of these moves might seem better than the others against a particular opponent. But making an objectively poor move in the hopes that your opponent will not find the refutation is asking for punishment.
  
  By far the primary means of adjusting one's style to one's opponent is selecting the opening. For example, the Sicilian Defense and the French Defense are both good choices objectively, but you might have reason to believe your opponent will perform worse against the Sicilian than the French. But if you know the French better than the Sicilian, you should probably choose the French, or else your choice of opening might hurt you more than your opponent.
  
  This isn't the sort of thing most players really need to worry about until they become quite strong (master level). Usually in a tournament game you should just make the moves you're most comfortable with and play the moves that seem objectively best.
  
  > **Comments:**
  > **username_1**: It's too bad that this answer comes so late. Hopefully it won't stay buried at the bottom of the answer column! It is the best answer so far.  
  > **username_4**: I would stress that for almost anyone looking to improve their ability, it would be better to learn to find objectively stronger moves instead of trying to find weaker moves that might be better against specific opponents. You never know when your opponent will see through your weaker plan and refute it. But against the objectively strongest plan, there is no refutation! This is also very situational. It's rare that you'll know an opponent well enough to find a weaker move that is stronger against them. But sometimes in lost positions, a less optimal but "trickier" move can save the game.  
  
  ---
  
  ### Answer by username_5 on 2016-06-12. Score: 2
  
  Let me quote Botvinnik's words from a chess history book in Russian. It is about his preparation for his rematch against Tal after losing the champion's title to him.
  
  I decided to play working in two directions. Firstly, to take a lesson from Tal and become a tactical trickster. Secondly, to prepare openings and middlegame plans with a closed character so that the board is fragmented into separate regions, the pieces are little mobile, even if objectively my positions are worse, hoping that my opponent will not be able to make use of his ingenuity and memory, while my understanding of positions might tell.
  
  
  ---
  
  ### Answer by username_5 on 2016-06-11. Score: 2
  
  Botvinnik lost to Smyslov and to Tal in world championship matches and then won with them in rematches. From his writing it follows that he has studied the style of his opponents and learned to play against them. In playing against Tal in the rematch he avoided tactical complications in favor of dry endgames and that supposedly worked out. This is just an idea how to answer your question. One would need to investigate this line more deeply.
  
  > **Comments:**
  > **username_0**: Why did you wrote 3 different answers. You can merge all into one single answer here.  
  > **username_5**: @username_0 Each answer is different and can be evaluated and commented separately. These are things which may require a further discussion or improvement. It is actually a benefit that the interface allows multiple answers from the same user.  
  > **username_6**: Actually in the rematch against Tal the main change in Botvinnik's play (according to Tal at least) was that he became more confident, and didn't avoid complications. He tried the going for the endgame strategy in the first match, and it wasn't enough. Actually you quote the same in a later answer from Botvinnik.  
  
  ---
  
  ### Answer by username_5 on 2016-06-11. Score: 2
  
  The world champion Emanuel Lasker is reputed to be a master of psychology, adjusting his play to upset his opponents to the point of making inferior moves on purpose. This is just an idea to pursue in the literature. For example, Kasparov writes about it in his predecessor series.
  
  
  ---
  
  ### Answer by username_5 on 2016-06-11. Score: 2
  
  The young Bobby Fischer used to play the same opening scheme from game to game against every opponent. Later he adopted the element of surprise and varied his openings. I remember reading about it somewhere and it was worded so that the aspect of psychological battle became one of his tools contrary to his previous straightforward play.
  
  
  ---
  
  ### Answer by username_5 on 2016-06-11. Score: 2
  
  I remember reading about Taimanov's preparation against Fischer before the match which he famously lost 6 to nil. His helpers recommended him to play the French Defense because Fischer was known to be ineffective against it, but Taimanov disregarded this advice and played his favorite Sicilian Defense which was to Fischer's liking.
  
  
  ---
  
  ### Answer by username_5 on 2016-06-11. Score: 2
  
  I remember reading Carlsen's comments after his first match against Anand to the effect that he soon discovered that he needed no change from his usual play but was prepared to play differently. I don't remember any particulars as to this modified way of playing that he had prepared but at least this answers the question in the positive that this phenomenon is real in preparation against opponents.
  
  
  ---
  
  ### Answer by username_7 on 2016-07-10. Score: 0
  
  American master Fred Reinfield advised people to "play the man and not the board."
  
  While an opponent will have a given strength, X, s/he probably will not have the same strength in all types of games. It might be a strength of X+100 in positional games and X-100 in tactical games (or vice-versa).
  
  Say your rated strength Y, is X-50. But if your strength is X in tactical games and X-100 in positional games, knowing your opponent's (game) personality may enable you to match your X level of tactical play against his X-100.
  
  Some years ago, I was a 1500 player playing with two 1800 players. The two other players played evenly between themselves. I was "even money" against one of these two players because I was able to match my strength in positional games (relative to my rating) against his weakness in this area. I was a heavy underdog against the other player, who matched me positionally, but had better tactics than me.
  
  
  ---
  
  