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Understanding StockFish output


  • 6 months ago · Quote · #1

    kvnsndrs87

    Hello all!

    I have recently begun using the chess engine StockFish to analyze my games.  I gather that it is quite popular and thus I assume many of you understand how it scores games and moves.

    I understand the scoring system - kind of. I get that +(1.5) means white is essentially up 1.5 pawns, and likewise -(1.5), black.  However, I have an analysis now that looks like +(1.71)--.  What does this mean?  The game I am analyzing, I was playing as white, so I gather this means that I am up 1.71 pawns.  But I don't get what the -- means.

    Can someone explain what -, --, +, and ++ mean?  Thanks a lot.

  • 6 months ago · Quote · #2

    CalPolyJohn

    I don't get it at all but I am going to post in here so I remember to come back when somebody explains

  • 5 months ago · Quote · #3

    AaronShaverPDX

    I too would like to know this!

  • 5 months ago · Quote · #5

    EscherehcsE

    I also don't know. Maybe the GUI (chess program) is doing it. What GUI are you using?

  • 5 months ago · Quote · #6

    AaronShaverPDX

    Dale, I don't think that's the case. I entered some ridiculous moves where white has a huge advantage*, and the ++ and -- switch back and forth as the analysis spins.

    1. e4 h5 2. Nf3 a5 3. Nc3 a4 4. d4 h4 5. Be2 Rh7 6. O‑O Nh6 7. Nxh4 Ng8 8. Nf3 Rh8 9. Bf4 Rh7 10. Ng5 Rh8 11. d5 Rh7 12. Nxh7

  • 5 months ago · Quote · #7

    Fugazy_Crapov

    Here's a link discussing the signs.

    http://www.chessinformant.rs/system-of-signs/

    Don't get hung up on what +1.71 means versus +1.50, etc.

  • 5 months ago · Quote · #8

    AaronShaverPDX

    Fugazy_Crapov, Stockfish is not doing the typical +-, +=, etc. symbols. It's doing "--" and "++", which I think is something particular to this engine.

    Looks like http://www.talkchess.com/forum/ would be the place to ask, but I'm having trouble registering on that site.

  • 5 months ago · Quote · #9

    Fugazy_Crapov

    AaronShaverPDX wrote:

    Fugazy_Crapov, Stockfish is not doing the typical +-, +=, etc. symbols. It's doing "--" and "++", which I think is something particular to this engine.

    Looks like http://www.talkchess.com/forum/ would be the place to ask, but I'm having trouble registering on that site.

    What's your GUI?  Chess engines don't produce nuanced evaluation output.  They report plus or minus scores.  Some GUI's will add more elaborate symbols or comments.  The Shredder GUI will even display messages such as "+4.21 means white has a decisive advantage."  But these symbols and messages are from the GUI, which is interpreting and expounding upon the engine output.

    In any event, I'm not seeing the inexplicable output you describe, so perhaps a screen shot of the output will help.  It's possible, I suppose, that a given GUI might display flawed output due to a bug or a non-standard UCI implementation in Stockfish.  But it looks fine from here.  If you're  running Windows, try the Tarrasch GUI.  It displays basic output only, near as I can tell.

    http://www.triplehappy.com/

  • 5 months ago · Quote · #10

    AaronShaverPDX

    Here's an example of the "--" showing up:

    http://i.imgur.com/jl8XEj6.png

    This is from the official Stockfish Mac app.

  • 5 months ago · Quote · #11

    AaronShaverPDX

    Okay, I found an answer on reddit r/chess:

    "When an engine (stockfish or other) writes ++ or -- after the evaluation number, in the analysis window of your user interface software, it means the latest mainline it has considered during the search process it's performing in the possible moves' tree is significantly better for White (++) or Black (--) then the evaluation value calculated for the previous mainline."

    From: http://www.reddit.com/r/chess/comments/209xvm/could_someone_who_knows_about_the_stockfish/cg18we7

  • 5 months ago · Quote · #12

    Fugazy_Crapov

    AaronShaverPDX wrote:

    Okay, I found an answer on reddit r/chess:

    "When an engine (stockfish or other) writes ++ or -- after the evaluation number, in the analysis window of your user interface software, it means the latest mainline it has considered during the search process it's performing in the possible moves' tree is significantly better for White (++) or Black (--) then the evaluation value calculated for the previous mainline."

    From: http://www.reddit.com/r/chess/comments/209xvm/could_someone_who_knows_about_the_stockfish/cg18we7

    Good work!  I was going to suggest you just consider those symbols "noise."  I see those types of symbols in some GUI's (e.g. Fritz) but not in others.

  • 5 months ago · Quote · #13

    AaronShaverPDX

    Well, one thing that guy on reddit points out is you can use those symbols to tell when the engine has "settled down" in its analysis. If you're still seeing wild swings in evaluation, you should let the engine run longer. But if you haven't seen one of those ++/-- in awhile, you're probably safe that it's settled on the best move (or are at least close).

  • 5 months ago · Quote · #14

    Fugazy_Crapov

    AaronShaverPDX wrote:

    Well, one thing that guy on reddit points out is you can use those symbols to tell when the engine has "settled down" in its analysis. If you're still seeing wild swings in evaluation, you should let the engine run longer. But if you haven't seen one of those ++/-- in awhile, you're probably safe that it's settled on the best move (or are at least close).

    Good point.  I ended up learning here, too!


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