Answers.Body: <p>Using my free, open source <a href="https://www.cs.kent.ac.uk/%7Edjb/pgn-extract/" rel="noreferrer">pgn-extract</a> program you can specify a grep-like FEN pattern to be searched for in a PGN file of games. The program comes with a file of opening lines (eco.pgn) so a search such as:</p>
  <pre><code>pgn-extract --fenpattern &quot;*/*/*/*/3PP3/2P2P2/PP4PP/RNBQKBNR&quot; eco.pgn
  </code></pre>
  <p>would output any matches along with the associated ECO information in the tags. I didn't find anything for this particular pattern.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-04-14T06:43:58.197Z
Answers.LastActivityDate: 2021-04-14T06:43:58.197Z
Answers.UserDisplayName: kentdjb
Body: <p>Given a position for just one player, how can I check to see if there is a standard opening that leads to that position?</p>
  <p>For example, how could I find if there is an opening that leads (or may lead, if the line is followed by black) to a position like this for white?</p>
  <pre><code>[FEN &quot;8/8/8/8/3PP3/2P2P2/PP4PP/RNBQKBNR w KQ - 0 1&quot;]
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-14T06:19:32.093Z
Comments.Text: While this looks like after the fourth move, in theory this could be further into the game after e.g. a Four Knights Game
Comments.UserDisplayName: Hagen von Eitzen
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-14T06:33:04.687Z
Comments.Text: @HagenvonEitzen True! (I would also be interested in ways to find games based on the position of one player, which I guess both generalises and solves my original question on finding openings.)
Comments.UserDisplayName: badroit
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-14T07:01:30.360Z
Comments.Text: I don't know why you'd want to do such a thing but this doesn't look to me like any well known opening. Perhaps some setup against a fianchetto defense by Black, but definitely not the best option to counter it.
Comments.UserDisplayName: David
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-14T07:16:53.250Z
Comments.Text: Unsurprisingly, the more passive your wish structure (Hippo against all :-), the more probable you can play it against most answers of your opponent.
Comments.UserDisplayName: Hauke Reddmann
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-04-15T03:16:48.873Z
Comments.Text: I suspect you have just left the pieces on the original squares because you are looking for openings that make this pawn structure.  It is much less likely that you will achieve this position on the first four moves than that you will achieve this pawn structure with some of the pieces moved.  If that is really what you want you should improve the question.
Comments.UserDisplayName: Ross Millikan
Tags: <opening><database>
Title: Find an opening based on the position of one player only
ThreadText: # Find an opening based on the position of one player only
  
  (Asked by: username_0 on 2021-04-14)
  
  Given a position for just one player, how can I check to see if there is a standard opening that leads to that position?
  
  For example, how could I find if there is an opening that leads (or may lead, if the line is followed by black) to a position like this for white?
  
  ```
  [FEN "8/8/8/8/3PP3/2P2P2/PP4PP/RNBQKBNR w KQ - 0 1"]
  
  ```
  
  **Tags:** opening, database
  
  > **Comments:**
  > **username_1**: While this looks like after the fourth move, in theory this could be further into the game after e.g. a Four Knights Game  
  > **username_0**: @username_1 True! (I would also be interested in ways to find games based on the position of one player, which I guess both generalises and solves my original question on finding openings.)  
  > **username_2**: I don't know why you'd want to do such a thing but this doesn't look to me like any well known opening. Perhaps some setup against a fianchetto defense by Black, but definitely not the best option to counter it.  
  > **username_3**: Unsurprisingly, the more passive your wish structure (Hippo against all :-), the more probable you can play it against most answers of your opponent.  
  > **username_4**: I suspect you have just left the pieces on the original squares because you are looking for openings that make this pawn structure.  It is much less likely that you will achieve this position on the first four moves than that you will achieve this pawn structure with some of the pieces moved.  If that is really what you want you should improve the question.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_5 on 2021-04-14. Score: 8 | Accepted answer
  
  Using my free, open source [pgn-extract](https://www.cs.kent.ac.uk/%7Edjb/pgn-extract/) program you can specify a grep-like FEN pattern to be searched for in a PGN file of games. The program comes with a file of opening lines (eco.pgn) so a search such as:
  
  ```
  pgn-extract --fenpattern "*/*/*/*/3PP3/2P2P2/PP4PP/RNBQKBNR" eco.pgn
  
  ```
  
  would output any matches along with the associated ECO information in the tags. I didn't find anything for this particular pattern.
  
  
  ---
  
  