I have file Rybka.exe and when I use it for the first moves, it always goes Nf3 or Nc3 only (even at strength 1000 and depth 1). I assume that is because it doesn't have opening book assigned (?) to it. How does one connect opening books in .ctg (or other?) formats to the chess engine? I do not want to get some GUI, but rather understand how it is done.

  • Could you clarify your question? Is it normal practice to connect opening books to engines? You say that you don't want to get some GUI. But is it best practice to use GUI:s in this situation?
    – user2001
    Dec 2, 2013 at 20:26
  • Well, software like Fritz, if you play against it, plays various variations thus that means in some way it is done artificially, not using vanilla engine. Otherwise, it just picks the top move in the current position, which, given the same amount of time and CPU is always the same. It alternates between Nf3 and Nc3 because they both are quite equal moves. I assumed you can just make the engine use the opening book until it can be followed. Otherwise I am forced to find a way to read the book and supply the moves by myself. Dec 2, 2013 at 22:08
  • This does not seem to be a trivial question to answer. Perhaps you should do a deep search on Google and try to find the answer there. Or perhaps expand your question and add more information about exactly what Rybka version you have, what operating system you are using, what GUI:s you have already tried, and what exactly you are trying to achieve.
    – user2001
    Dec 15, 2013 at 1:49

2 Answers 2


I don't have Rybka 4 but I do have the free version (Rybka 2.3.2). Rybka 2.3.2 doesn't support engine book. To verify this, open the engine in command, then type "uci". Look at how I did it.

Look the UCI options, we have one for multi-pv and others. But there is nothing for an opening book. If the engine doesn't support an opening book, you have to rely on a GUI to do it, for example, Fritz.

On the other hand, if you do the same thing to Stockfish, you'll see a Book options where you can specify path to your book be used by the engine.

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It sounds like you're using the standard Chessbase interface when you mentioned a .ctg file. The Chessbase interface is used for many engines, so this title may work: How To Make Fritz Chess Software Play a Specific Chess Opening
Try this: http://www.chesscentral.com/Chess_Opening_Book_a/137.htm

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