Answers.Body: <p>Assuming the engine performing the analysis is Stockfish (sounds reasonable, since the engine is presumably running on CPU) then it's probable the move it considers subpar is 4.c3. Left to its own devices Stockfish <em>will</em> occasionally play the Giuoco Piano, but it will usually play the Giuoco Pianissimo - i.e. 4.d3 instead of 4.c3.</p>
  <p>Indeed, the cloud analysis by Stockfish 11 at lichess.org/analysis gives, at depth 45, +0.3 for 4.d3 compared to +0.2 for 4.c3. You can also check out the SF-Lc0 <a href="https://tcec-chess.com/#div=rapidfl&amp;game=17&amp;season=bonus" rel="nofollow noreferrer">bookless bonus</a> TCEC ran in 2019. There were ten Italian games, all played by Stockfish, and of these games 9/10 continued with 4.d3.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-24T09:15:26.497Z
Answers.Text: But `1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 d6 5. d4 Bb6` gives a score of 100%. So it doesn't seem like 4.c3 is the culprit.
Answers.UserDisplayName: D M
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Answers.CreationDate: 2020-08-04T04:41:13.050Z
Answers.LastActivityDate: 2020-08-04T04:46:45.667Z
Answers.LastEditDate: 2020-08-04T04:46:45.667Z
Answers.UserDisplayName: Allure
Answers.Body: <p>Probably, as you pointed out, Bb5 instead of Bc4.</p>
  <p>The Ruy Lopez is considered very very marginally better/more critical than the Italian by humans, so it'd make sense that the engine used here'd agree.</p>
  <p>Certainly, however, the Italian is fine, and the difference is very marginal.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-08-02T02:49:21.527Z
Answers.Text: Running the moves on chess.com/analysis we see that all white’s moves match the engine’s top move except 3. Bc4. It seems reasonable to assume that the engine used to give an accuracy score is the same as the one they use for their analysis board.
Answers.UserDisplayName: DongKy
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Answers.Text: Thank you for the answer! Talking about be very marginal accuracies, after 1. e4, is e5 very marginally better than c5 or c6 or e6?
Answers.UserDisplayName: Zuriel
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-08-02T04:18:08.960Z
Answers.Text: e5 is (probably) very marginally better than e6 and c6, but it's not so clear for c5.
Answers.UserDisplayName: pulsar512b
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Answers.CreationDate: 2020-08-03T22:46:27.970Z
Answers.Text: Stockfish actually has a thing for the French.
Answers.UserDisplayName: David Miedema
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-08-12T16:17:53.610Z
Answers.Text: I think probably just SF being weird. It loves the French for some ungodly reason.
Answers.UserDisplayName: pulsar512b
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Answers.Text: If you just put `1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 d6 5. d4 Bb6` into the analysis, it gives White 100%. So the speculation that it's downgrading the Italian doesn't seem to hold water.
Answers.UserDisplayName: D M
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Answers.UserDisplayName: pulsar512b
Body: <p>Here is a short game played online at chess.com.</p>
  <pre><code>[FEN &quot;&quot;]
  
  1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 d6 5. d4 Bb6 6. dxe5 
  </code></pre>
  <p>Black resigned for some unknown reason; maybe a mouse slip or he/she needs to leave. When the game was analysed at chess.com, the game accuracy of white is 99.7%. In my humble opinion, every White move is accurate (unless one considers 3. Bb5 to be more accurate than 3. Bc4). But why is the game accuracy for white is not 100%? What is the 0.3% that White l missed?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-03T07:06:15.323Z
Comments.Text: Can you show which entity did the analysis that got 99.7% accuracy? (a link to the analysis would be best)
Comments.UserDisplayName: Allure
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-03T11:12:28.787Z
Comments.Text: After reading only the title, I thought this is a Breaking Bad question.
Comments.UserDisplayName: Shadov
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-03T15:39:33.527Z
Comments.Text: @Shadov what would be the breaking bad connection?
Comments.UserDisplayName: pulsar512b
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-03T15:49:07.700Z
Comments.Text: @pulsar512b: The main character's name is [Walter White](https://en.wikipedia.org/wiki/Walter_White_(Breaking_Bad)).  IDK what Shadov had in mind for accuracy; possibly mixing chemicals (something the character was excellent at).
Comments.UserDisplayName: Peter Cordes
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-03T18:32:07.020Z
Comments.Text: @pulsar512b As above. About accuracy - it's a big thing in the show that Walter White's meth purity is, if I remember correctly, 99.1%. That is the main reason he becomes so successful - it's a lot better than the regular street-meth.
Comments.UserDisplayName: Shadov
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-04T04:32:47.417Z
Comments.Text: @allure, here it is: https://www.chess.com/analysis/game/live/5238304345
Comments.UserDisplayName: Zuriel
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-08-04T06:09:03.543Z
Comments.Text: 99.7% accuracy means the exact same thing as 100% accuracy
Comments.UserDisplayName: David
Tags: <opening><engines><analysis><italian-game>
Title: Why is White's accuracy 99.7% instead of 100.0%?
ThreadText: # Why is White's accuracy 99.7% instead of 100.0%?
  
  (Asked by: username_0 on 2020-08-02)
  
  Here is a short game played online at chess.com.
  [FEN ""]
  
  1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 d6 5. d4 Bb6 6. dxe5 
  
  Black resigned for some unknown reason; maybe a mouse slip or he/she needs to leave. When the game was analysed at chess.com, the game accuracy of white is 99.7%. In my humble opinion, every White move is accurate (unless one considers 3. Bb5 to be more accurate than 3. Bc4). But why is the game accuracy for white is not 100%? What is the 0.3% that White l missed?
  
  **Tags:** opening, engines, analysis, italian-game
  
  > **Comments:**
  > **username_1**: Can you show which entity did the analysis that got 99.7% accuracy? (a link to the analysis would be best)  
  > **username_2**: After reading only the title, I thought this is a Breaking Bad question.  
  > **username_3**: @username_2 what would be the breaking bad connection?  
  > **username_4**: @username_3: The main character's name is [Walter White](https://en.wikipedia.org/wiki/Walter_White_(Breaking_Bad)).  IDK what username_2 had in mind for accuracy; possibly mixing chemicals (something the character was excellent at).  
  > **username_2**: @username_3 As above. About accuracy - it's a big thing in the show that Walter White's meth purity is, if I remember correctly, 99.1%. That is the main reason he becomes so successful - it's a lot better than the regular street-meth.  
  > **username_0**: @allure, here it is: https://www.chess.com/analysis/game/live/5238304345  
  > **username_5**: 99.7% accuracy means the exact same thing as 100% accuracy  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_3 on 2020-08-02. Score: 19 | Accepted answer
  
  Probably, as you pointed out, Bb5 instead of Bc4.
  
  The Ruy Lopez is considered very very marginally better/more critical than the Italian by humans, so it'd make sense that the engine used here'd agree.
  
  Certainly, however, the Italian is fine, and the difference is very marginal.
  
  > **Comments:**
  > **username_7**: Running the moves on chess.com/analysis we see that all white’s moves match the engine’s top move except 3. Bc4. It seems reasonable to assume that the engine used to give an accuracy score is the same as the one they use for their analysis board.  
  > **username_0**: Thank you for the answer! Talking about be very marginal accuracies, after 1. e4, is e5 very marginally better than c5 or c6 or e6?  
  > **username_3**: e5 is (probably) very marginally better than e6 and c6, but it's not so clear for c5.  
  > **username_8**: Stockfish actually has a thing for the French.  
  > **username_3**: I think probably just SF being weird. It loves the French for some ungodly reason.  
  > **username_6**: If you just put `1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 d6 5. d4 Bb6` into the analysis, it gives White 100%. So the speculation that it's downgrading the Italian doesn't seem to hold water.  
  
  ---
  
  ### Answer by username_1 on 2020-08-04. Score: 1
  
  Assuming the engine performing the analysis is Stockfish (sounds reasonable, since the engine is presumably running on CPU) then it's probable the move it considers subpar is 4.c3. Left to its own devices Stockfish *will* occasionally play the Giuoco Piano, but it will usually play the Giuoco Pianissimo - i.e. 4.d3 instead of 4.c3.
  
  Indeed, the cloud analysis by Stockfish 11 at lichess.org/analysis gives, at depth 45, +0.3 for 4.d3 compared to +0.2 for 4.c3. You can also check out the SF-Lc0 [bookless bonus](https://tcec-chess.com/#div=rapidfl&game=17&season=bonus) TCEC ran in 2019. There were ten Italian games, all played by Stockfish, and of these games 9/10 continued with 4.d3.
  
  > **Comments:**
  > **username_6**: But `1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 d6 5. d4 Bb6` gives a score of 100%. So it doesn't seem like 4.c3 is the culprit.  
  
  ---
  
  