- REBEL 11.0 and CAT -

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CAT (Computer Analysis Tool)

CAT is a new type of database similar to the EOC approach. While EOC chess trees focus on human games CAT is a chess tree for computer analysis only. CAT is "the" way to organize your computer-computer databases (games and/or positions).

CAT trees can be easily created from a Rebel database. A CAT test database made from SSDF games mainly and enriched with games from other sources will give the following informations:

  • Picture-1 : a typical Sicilian opening. Rebel Century 1.2 played 6.g3 exactly 5 times and scored 60% in this opening. The move 6.g3 is in all program's opening book. The CAT database contains 99.033 unique positions. 20.643 positions were found in the program's opening books. The average ply-depth of all programs in the CAT database is 12 plies deep. For "Book Hits" and "Engine hits" see further.

  • Picture-2 : scrolling one page down in the CAT info window gives the totals for each engine in the CAT database. For Rebel the totals are a total of 8932 positions of which 1578 are played from Rebel's opening book. Furthermore Rebel's average ply-depth was 10 plies deep based on all games.

  • Picture-3 : example of a game played between Rebel Century 1.2 and Fritz 5.32 while both programs have left the opening book. The move 12.Qd2 is played twice, Rebel having won twice. The ply-depth, score and main variation is also given for 12.Qd2. The latter is only possible with Rebel-Century and Rebel-Tiger as these 2 programs are the only ones that write the full main variation to stored games. With other programs the depth, score and the move played is visible.

  • Picture-4 : is perhaps the most fascinating option of CAT databases. When a position is found in the CAT database it will use the information and most of the time Rebel Century 3.0 is able to compute one ply deeper because of that. The screenshot shows this in action, within a few seconds the fist 11 plies are done and Rebel is going one ply deeper.

  • The engine when information is found in the CAT database mainly will rely on Rebel's own analyis but the engine (on request) will also use the data of other chess engines. When this option is activated Rebel is happy to play from other opening books (in this way being always longer in the book than the opponent!) or use the information of other engines as a guide line for its own decisions.

  • When Rebel plays a book move from another opening book than its own the counter "Book Hits" is incremented. When the Rebel engine uses an entry from the CAT database for its calculations the "Engine Hits" counter is incremented. See Picture-1.

  • Organizing positions with CAT

  • Besides storing games in a CAT chess tree you can also import positions (test suites) in a CAT chess tree with analysis from several chess programs and compare the results to make up your mind which engine does the best job in a particular position. 3 examples are given.

  • Picture-5 : the critical position of game-7 of the Anand-Rebel match in 1998. Rebel 10.0 was too greedy and collected the material gain with 1...Bxb2+ not realizing Anand could escape brilliantly 10 moves later with a draw. The winning move 1...Qe6! which increases the pressure on the white king even more is no problem for Rebel Century and Rebel Tiger.

  • Picture-6 : 1. Bxd6! is a fine long-term positional sacrifice that exposes the black king to a decisive king attack by white. Rebel Century 3.0 seems to be the only program that gets the idea.

  • Picture-7 : one of the critical positions of Rebel's first game in the GM challenge against GM Michael Rohde. Rebel then played 1.exd4? where 1.Rxb4 is the much better move. Apparently this is still a difficult move for many chess programs. Even Rebel Century 3.0 needed 12 plies to see that Rxb4 is the better move.

  • Automatic learning with CAT

  • Each game you play or every position you analyze is automatically stored in a special CAT chess tree called REBLEARN. There are several advantages for you the end-user but also for the Rebel chess engine.

  • REBLEARN can be seen as the graphical representation of learning. If for instance the statistic for 1.e4 c5 2.b3 is only 25% after 4 games (so 1 draw) Rebel will lower the priorty of 2.b3 in the opening book. If the move 2.b3 is played after all because of the random nature of an opening book Rebel will deal with the problem later in the game.

  • The advantage for you the end-user is that you immediately can see the Rebel score of each particular opening (number of games + the percentage) you have played since you have installed Century 3.0 on your hard disk. If you have a bad score against Rebel with 1.d4 Nf6 then just try 1..d5 for a change.

  • Picture-9 : an example made from the 353 games played against various computer opponents shows one of the critical positions of the Najdorf defence of the Sicilian. White has many posibilities. The statistic show how well (or bad) Rebel did.

  • the REBLEARN option can be turned on or off. REBLEARN can be emptied too (clear learning).

  • CAP support

  • CAP stands for "Computer Analysis Project". CAP is the initiative of Danniel Corbit who with his team has analyzed over 1,000,000 positions on very long time controls. The second nice thing about CAP is that all analysis contains the main variation of each engine. The one million CAP data is full of positions of well known computer test suites. An example:

  • Picture-8 : a position from the famous LCT-II test suite. The position is found in Dann's 1,000,000 CAP data for Rebel and Crafty and Rebel Century 3.0 retrieves the key-move 1.Bb4! immediately from the database.

  • The latest data of Danniel Corbit's project (over 1,000,000 positions) will be available on the REBEL 11.0 cdrom. Updates are available from Dann's pages (or via the "REBEL Subscription Area") and easily can be added using the option "Import EPD to CAT".

  • I want to know more, move me to the Computer Analysis Project pages.

  • Creating and maintaining big CAT chess trees

    Creating CAT chess trees is easy and various data input possiblities are at your service, such as:
    • Output from (any) auto232 games (the SSDF games comes to mind).
    • Output from Rebel's engine-engine matches (by playing many matches you automatically make Rebel a bit stronger!)
    • Output from the popular ChessBase engine-engine matches.
    • Using suitable EPD files such as the CAP data from Danniel Corbit or the output from Rebel's function "Analyze EPD".
    Many tools to create and maintain CAT chess trees are available:
    • Create a new (and empty) CAT database.
    • Load a CAT database.
    • Import CAT via Rebel databases.
    • Import CAT via EPD files.
    • Merge CAT (merge 2 CAT databases into 1).
    "Merge CAT" is extremely handy for auto232 lovers. Every time you have finished an auto232 session with Rebel Century 3.0 just merge the automatically created REBLEARN into the CAT database of your choice.

    Providing data to build your own CAT chess trees

    On the Rebel 11.0 cdrom you will find the following CAT databases:
    • All suitable public computer-computer games provided by the SSDF (*)
    • A large CAT database from all suitable auto232 games.
    • Danniel Corbit's 1,000,000 positions stored in CAT.
    Plans for the Rebel Subscription Area are:
    • When available provide updates for the SSDF CAT database (*)
    • When available provide updates from the Danniel Corbit CAP project.
    • When available provide updates for REBLEARN.
    • Open a section where users can submit own made CAT databases and exchange them.

    * Maintaining the SSDF games database is the work of Tony Hedlund one of the leading SSDF members. Tony's work and databases can be found on his pages.

    CAT and FAQ (frequently asked questions)   

  • [Q]  It is said Rebel can use the CAT data for its own analysis, how do I do this?


  • MODERATE: Rebel will use the analysis of Rebel, Rebel-Tiger and even use the book moves of Fritz and Nimzo for its own calculation. This option is highly recommended in case you have loaded the provided CAT database COMPCOMP.EOC (found in the CAT directory) or REBLEARN.EOC (found in the root directory).

    STRONG: Rebel will use the analysis of Rebel, Rebel-Tiger, Fritz, Crafty and even use the book moves of Fritz, Nimzo, Shredder, Junior and Hiarcs for its own calculation. In a way (provided you have a huge CAT database) you can emulate the play of all these chess engines. The STRONG setting is not recommended for maximum playing strength. If you use the STRONG option it is advised to load the big CAP.EOC database (provided on cdrom in the CAP directory) of 1,000,000 positions or use the CAT database COMPCOMP.EOC (found in the CAT directory).

  • [Q]  I have imported a lot of games into CAT but I don't see any (new) positions?

  • [A]  Games MUST contain computer analysis otherwise there is nothing to store into CAT.

  • Typical suited are:
    • Output from (any) auto232 games (the SSDF games comes to mind).
    • Output from Rebel's engine-engine matches (by playing many matches you automatically make Rebel a bit stronger!)
    • Output from the popular ChessBase engine-engine matches.
    • Using suitable EPD files such as the CAP data from Danniel Corbit
    • The output from Rebel's function "Analyze EPD".

  • [Q]  I have analyzed an EPD file with "Analyze EPD" but when I import the data into CAT I don't see the new added positions?

  • [A]  "Analyze EPD" stores the output in a special file DD-MM-YY.EPD (day, month, year) to secure your data. You should import this DD-MM-YY.EPD file into CAT.

  • [Q]  Sometimes Rebel is busy for 5-10 seconds (or longer) with the hard disk, what is happening?

  • [A]  This can happen when you have created a big REBLEARN database in your root directory and also have "Learning=ON" (see menu BOOKS). The cure is to clear the REBLEARN database (clear learning) or set "Learning=OFF"

  • Explanation: when "Learning=ON" Rebel will automatically store analysis into REBLEARN from time to time while you play your games or analyze positions. Its goal is to record every analysis Rebel has made and use it afterwards. When REBLEARN grows and grows the delay will of course grow too.


    Deventer, February 3 2001

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