Answers.Body: <p>Given a legal position, the same position with colors swapped (and rows mirrored) is legal, apart from a very small number of exceptions like the position after <code>1.a3</code>. So the average evaluation must be very close to 0.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-11-11T14:54:07.200Z
Answers.Text: Actually, small correction: the position after `1.e4` is legal even with colors swapped because black can lose a tempo with the queen or bishop: `1.Nf3 e5 2. Ng1 Be7 3. Nf3 Bd6 4. Ng1 Bf8`. An example of a legal position that becomes illegal after swapping colors is the one after `1. a3`, since one cannot lose tempi moving just the rook and knight.
Answers.UserDisplayName: Federico Poloni
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-11-11T13:59:59.310Z
Answers.LastActivityDate: 2022-11-11T14:55:08.743Z
Answers.LastEditDate: 2022-11-11T14:55:08.743Z
Answers.UserDisplayName: Federico Poloni
Body: <p>Would it be accurate to expect a random legal position to tend to evaluate to a white advantage? How does the distribution of evaluations look like?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-11-11T14:40:08.077Z
Comments.Text: The side to move would have the advantage on average.  Is side to move part of randomization?
Comments.UserDisplayName: Michael West
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-11-11T17:12:30.903Z
Comments.Text: @MichaelWest Yes
Comments.UserDisplayName: 2080
Tags: <engines><statistics>
Title: What engine evaluation does the average randomly generated legal position have?
ThreadText: # What engine evaluation does the average randomly generated legal position have?
  
  (Asked by: username_0 on 2022-11-11)
  
  Would it be accurate to expect a random legal position to tend to evaluate to a white advantage? How does the distribution of evaluations look like?
  
  **Tags:** engines, statistics
  
  > **Comments:**
  > **username_1**: The side to move would have the advantage on average.  Is side to move part of randomization?  
  > **username_0**: @MichaelWest Yes  
  
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  ## 1 answers
  
  ### Answer by username_2 on 2022-11-11. Score: 4
  
  Given a legal position, the same position with colors swapped (and rows mirrored) is legal, apart from a very small number of exceptions like the position after `1.a3`. So the average evaluation must be very close to 0.
  
  > **Comments:**
  > **username_2**: Actually, small correction: the position after `1.e4` is legal even with colors swapped because black can lose a tempo with the queen or bishop: `1.Nf3 e5 2. Ng1 Be7 3. Nf3 Bd6 4. Ng1 Bf8`. An example of a legal position that becomes illegal after swapping colors is the one after `1. a3`, since one cannot lose tempi moving just the rook and knight.  
  
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