An opening book for a chess engine is a collection of chess knowledge about different openings, which allows to significantly increase the playing strength of the engine.

To enable the engine to use different chess books, check the “Books” option in the “Engine settings” menu.

To select an opening book for use, proceed as follows:

Check the option “Use opening book” to select an opening book for use (if none has been selected yet). The program displays a file selection window showing the Chess Academy opening books with the extension .OBB. Select a book and click on the Open button. Alternatively, double-click on the relevant file with the mouse pointer or, after selecting a file, simply press the Enter key. If you want to prevent the engine from continuing to play moves from the book, simply unmark it again under “Use the opening book”. However, the program remembers the last book you set and its path. If you want to use the book again, you only need to select the option again.

Please note:

1. you must not only select an opening book for the engine but also for the opening editor. 2. you must select an opening book for both the engine and the opening editor.

Both the engine and the editor give an error message if the opening index (*.OBX) belonging to the book is not in the same directory as the file with the extension (*.OBB). In other words, both files always belong to an opening book. Once you have successfully selected a book, it is possible to specify advanced functions for a book.

The first thing you can specify here is the book depth, i.e. the maximum depth to which the engine uses the book. By default, the maximum depth is 52 half-moves. Next, you can specify the criteria by which the engine selects moves from the book.

Three alternatives are possible:

• Strength – With this setting, the program plays the moves that have the highest rating or enjoy preference (if any);
• Second best moves – If two moves exist, the program always selects the one with the second highest rating;
• Random – The program internally evaluates each move and randomly selects one depending on the rating. In other words, if one move has a rating of 2000 and another has a rating of 1000, the higher-rated move is played about twice more often. This reduces the playing strength a little but offers more variety when playing against the computer.

Without the opening book, the computer will not play very strong because the program of course can not compensate for a huge human knowledge based on decades of experience and top analysis of key opening positions with a few seconds or minutes of computing by the engine. On the contrary, with the opening book, the program will move instantly when it can find a book move and will not waste a lot of time in such a case.

Chess Academy contains two large opening books: a special Gambit Book (appr. 2.255.000 opening positions) to improve your skill in playing gambits, and a powerful Champion Book (appr. 9.500.000 opening positions). Use the Chess Academy Champion Book to achieve the best results playing with the Chess Academy Engine. Chess Academy does not account for moves from games with bad statistics to avoid typical mistakes.

However, there is also a chance to build a new opening book which will include your own game’s collection or the latest game’s update for example.

To do so:

Perform a search and build a dataset on the desired criteria (French defense or games played with Dr. A. Alekhine e.g.); save the resulting dataset if necessary. Alternatively: load the necessary dataset from the archive;

Then:

build a tree on the dataset;

from the Dataset menu, choose Create Opening Book… command, and therefore skip tree building.

or press “Create opening book” from the file menu (if you have already created a tree).

The program will then open a file selection window where they only need to specify a name for the opening book to be created. The extender .OBB will be added to the name automatically. In addition, the program automatically creates a file of the same name with the extender .OBX – this is the index file of the opening book. By default, all books and their indexes are stored in the Chess Academy subdirectory /BIN/BOOKS. Select the desired name and press the Save button, or double-click the desired name and press the Enter key.

As a result, the program will start the process of book creation based on the current tree. The process is accompanied by a special report with scrollbars that provides information about the creation. You can stop the creation at any time by pressing the “Cancel” button.