- REBEL 10.0 Playing Strength-


The Rebel chess engine has been modified in many ways. First, the search algorithm is rewritten from scratch resulting in better tactics. A second and main improvement is that the new chess engine is less selective than Rebel9 which also gives better results.

REBEL10 comp-comp tournament victory

REBEL10 (in Germany) recently won the strongest computer-computer event held ever. In 14 games REBEL10 scored 10 points without losing one single game.

All participants were in agreement, that REBEL10 played the best chess and won well-earned. The tournament was played as a seven-round-swiss system tournament with three hours each side for the wohle game.

For a full report of the event by Karsten Bauermeister CLICK HERE

Final Ranking
 1. Rebel 10		10/14

 2. Fritz 5.32		 9,5

 3. Hiarcs 7		 8,5

 4. Nimzo 3.5 / 99	 8

 5. Chessmaster		 7,5

 6. Zarkov 4.3		 7

 7. M-Chess Pro 8	 7

 8. Virtual Chess	 7

 9. Junior 5		 7

10. Shredder 3		 6,5

11. Chess System Tal	 6,5

12. Genius 5		 6,5

13. Kallisto II		 6

14. Gandalf 3		 5,5

15. Tasc R30 Vers.2,5	 2,5

  • Download all (105) games in REBEL format
  • Download all (105) games in PGN format

    REBEL10 prolongs its title in the SAMANEL cup

    4ta. COPA SAMANEL  1998
                                        1  2  3  4  5  6  7  8  9 10
     1  REBEL 10 400MHZ 128RAM    2555  *  1  ½  ½  1  1  1  1  ½  1    7.5
     2  CM6000 450MHZ 128RAM      2545  0  *  1  1  ½  ½  1  1  1  1    7.0
     3  HIARCS 6.0 350MHZ 128RAM  2550  ½  0  *  ½  1  1  1  1  1  1    7.0
     4  FM JOSE ML. DOMINGUEZ     2340  ½  0  ½  *  0  1  1  1  1  1    6.0
     5  IM NELSON PINAL           2325  0  ½  0  1  *  1  ½  ½  ½  ½    4.5
     6  NM NELSON ALVARADO        2180  0  ½  0  0  0  *  1  1  1  1    4.5
     7  IM RAMON MATEO            2470  0  0  0  0  ½  0  *  ½  1  1    3.0
     8  FM MARINO FERNANDEZ       2225  0  0  0  0  ½  0  ½  *  1  1    3.0
     9  ALEXIS MONTES DE OCA      2130  ½  0  0  0  ½  0  0  0  *  1    2.0
    10  NM JUAN ML. JAQUEZ        2205  0  0  0  0  ½  0  0  0  0  *    0.5
    Abbreviations: FM  FIDE Master
                   IM  International Master
                   NM  National Master
    As last year REBEL10 did not lose one single game. In 9 rounds REBEL10 scored 7½ points. In the comp-comp confrontation REBEL10 beat ChessMaster 6000 and draw against Hiarcs 6.0. CLICK HERE for full story.

  • Download available games in PGN and REBEL format

    A special piece of software has been added to the chess engine of Rebel10. It's a new development which we have called anti-GM (anti grandmaster play) which has as main purpose to avoid games which we consider as bad for Rebel when facing strong grandmasters.

    anti-GM will try to enter positions which we consider to be good for Rebel or in other words try to enter positions where Rebel's evaluation is very accurate. Also anti-GM is about to keep the initiative.

    Rebel10 anti-GM had its baptism of fire against world's second best chess player Vishy Anand in Italy (July 1998) where Rebel10 won the 8 game match with 5-3. In MOST games Rebel10 was able to keep the initiative and to set the rules of the games which we believe was the base of the victory against Anand.

    A special tactical search has been added to Rebel10's chess engine. These days (instead of playing normal games) solving difficult tactical positions with the help of a chess program becomes more and more popular. Rebel10's special tactical search will find key-moves up to 10 times faster.

    The maximum hash table size has been extended from 60 to 120 Mb. We believe this will make Rebel10 a bit stronger.

    The new engine under the microscope

    Playing strength (hash tables)

    The hash table sizes have been improved to today's standards. With Rebel10 you can use up to 120 Mb hash tables (was 60 Mb). Further, more attention is spent to avoid swapping of the Win95 swap-file when using big hash tables.

    As in Rebel9 also within Rebel10 you can specify the hash table size according to your own wishes. From the pull-down menu you have 16 choices. These 16 choices are upgraded to today's standards. The flexible hash table size for Rebel10 looks as follows:
        0 Kb   512 Kb    1 Mb    2 Mb    4 Mb    6 Mb    8 Mb   10 Mb
       13 Mb    20 Mb   28 Mb   40 Mb   60 Mb   80 Mb  100 Mb  120 Mb
    Also the command-line parameters are updated, the table for Rebel10 looks as follows:

    REBEL W1   512 Kb
    REBEL W2     1 Mb
    REBEL W3     2 Mb    best value for the use of a   4 Mb Pc
    REBEL W4     4 Mb    best value for the use of a   8 Mb Pc
    REBEL W5    13 Mb    best value for the use of a  16 Mb Pc
    REBEL W6    28 Mb    best value for the use of a  32 Mb Pc
    REBEL W7    40 Mb    best value for the use of a  48 Mb Pc
    REBEL W8    60 Mb    best value for the use of a  64 Mb Pc
    REBEL W9   100 Mb    best value for the use of a 128 Mb Pc (or higher)
    We expect these changes will make Rebel10 even more stronger.

    Playing strength (problem solving)

    Because many people (besides playing games and analysis) also use a chess program for solving difficult chess positions Rebel10's chess engine has been improved on several points resulting in incredible improved solution times.

    Rebel10 when analysing a position (automatically) will activate a special search algorithm that is fully tactical based and will find key moves up to 500-1000% faster. The average performance of finding key moves faster is estimated at 250-300%.

    If you don't like this special tactical search while analysing a position you can turn this option off in the OPTION menu COMBINATION=OFF as the default is COMBINATIOM=ON. The special tactical search is only active for finding the key move of the position (the first move of the position).

    To give you an impression about the performance of this new tactical search for positions you can compare the solution times for Rebel 9.0 versus Rebel 10.0 valid for the following 10 examples.

    Playing strength (bug fixes)

    • When a clear better move is found (Rebel shows the + sign) Rebel10 will immediately display this move in the main variation. This will increase the solution times for problem solving between 25-50%.

    • Fixed Rebel 9.0's display bug in cases when a very deep mate combination is found. Rebel10 now will show now the correct mate line, see the following example:

      00:00:00 2.01 Mate in 30 moves Ne3-g4+ Ke5-f5 Ng4-h6+ Kf5-e5 Nh6-f7+ Ke5-f5

      Please note that the complete mate is found in less than one second!

    ANTI Grandmaster play

    This new piece of chess knowledge for Rebel 10.0 has been especially developed for the upcoming match REBEL vs ANAND.

    The anti-GM software serves multiple purposes. Since we expect Vishy Anand will prepare on Rebel 9.0 (this due Rebel 9.0 is general available which we estimate as a huge disadvantage for this match) the anti-GM software will try to play a much different style of chess than Rebel 9.0, this without the loss of playing strength.

    Next the anti-GM experiment will try to provoke strong grandmasters like Vishy Anand to enter types of positions which are good for computers, in other words Rebel will try to create positions where it will play on its best (positions Rebel usually is very accurate) and avoid positions which we consider as a disadvantage for Rebel.

    The last months a lot of development time has been spent on this anti-GM option. The opinion about this experimental anti-GM software has been asked on several people who returned satisfying answers.

    The anti-GM software is available from the pulldown menu and has 4 options.
    • OFF Rebel will keep its usual positional style.
    • ACTIVE The anti-GM chess knowledge is activated but its use is a bit careful.
    • STRONG The anti-GM algorithm in its full glory.
    • SMART Rebel10's default setting. Rebel10 will use the anti-GM chess knowledge in a smart way depending on the current position (game). Depending on the status of the game (type of the position) Rebel10 will decide what to use (OFF, ACTIVE or STRONG).
    ANTI Grandmaster play (example)

    Position after Ra8-c8

    • Normally it takes Rebel 2:15 and 8 plies to find the sacrifice Rxe6! the score going from -0.84 to 0.09

    • Using anti-GM is ACTIVE Rebel will find the sacrifice in 0:03 on ply-5 with a score of -0.64

    • anti-GM set to STRONG does an even better job, Rxe6! is also found in 3 seconds on the fifth ply but the score is -0.42 now.

    Later in the search the Rebel score for Rxe6 will (of course) increase. Rex6 at ply-6 scores -0.14. Rxe6 at ply-7 scores -0.02. And finally at ply-8 Rxe6 scores 0.09 with an exact equal main variation and score as in normal play. The latter (the exact equal main varaiation and score) is more or less accidental and does not mean this will always be the case.

    In other words Rebel (using anti-GM) does not need to know the sacrifice is 100% correct for this position, Rebel smells the chance of an attack and goes for it!
    We certainly believe using the setting anti-GM=SMART Rebel10 will have a better chance against Vishy Anand next month. Also we believe it makes Rebel10 an overall stronger chess player. Finally we believe the anti-GM option makes Rebel's playing style even more attractive.

    ANTI Grandmaster play (more examples)


    Rebel is famous for its playing strength but especially for its deep positional understanding. Therefore the quality of the returned analysis is simply high and mostly very reliable what makes Rebel not only play good against humans but also against other computer opponents.

    In the period of 1991 till 1998 Rebel participated in the following main events:

    Year Event Place Result
    1991 World Micro Championship Vancouver World Champion
    1992 World Championship All Classes Madrid World Champion
    1993 World Micro Championship Munich 5th place
    1994 None --- ---
    1995 World Championship All Classes Hong Kong 6th place
    1996 None --- ---
    1997 Rebel9 versus Arthur Yusupov Italy 10½ - 6½
    1998 Rebel10 versus Vishy Anand Italy 5 - 3
    1991-1997 AEGON Man versus Machine The Hague Strongest computer
    1991-1998 SSDF (computer vs computer) Sweden Many first places

    We can't mention another chess program (with the exception of Deep Blue) that comes even close to the results of Rebel and especially not in respect to Rebel's performance against strong human chess players like Arthur Yusupov and world's second best chess player Vishy Anand.

    Related Links
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    Last update March 26, 1999

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