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REBEL 11.0 review

by Keith Kitson


I have to say this is the most versatile and comprehensively specified DOS based chess program on the market.  Ed Schroeder and his team have solved the assignment of Hash Ram to a DOS shell program running within the windows environment.  Two other notable DOS based programs MCP8 and Hiarcs 7.0/7.01 are not able to assign the same levels of Hash (i.e. upto 400Mb with Rebel, depending on available memory on the system) running within a DOS shell.

The refinements built into successive versions have rendered Rebel as windows like as possible.  A comprehensive, intuitive, context sensitive help facility, pull down menus, right click context sensitivity, comprehensive layout facilities, this program has all the conveniences one would expect of a mature chess program.

Position setup mode is a pleasure to use, it being so easy and intuitive. Truly international in nature Rebel caters for 6 languages, although I stick with English, more than a handful for me.

The EOC (Encyclopaedia Of Chess) facility has been enhanced and a utility is provided to convert old EOCs to the new more efficient format.  The EOC supplied with REBEL has 20 million unique chess positions!

A slight change in approach has been made to the default layout to cater for the presentation of more feedback information on the current position or game in progress.  The default board layout has been reduced to 75% to accommodate this.  Many other alternative layouts are available, and the user has the opportunity to define their own layout by right-clicking and dragging the individual windows as required, then saving the new layout for future use.

CAT (Computer Analysis Tool) database, is a new feature provided with this release.  It is a database mechanism allowing the orderly storage of computer v computer games and computer analysis for quick recall as required.  The big advantage of CAT is it can be switched into the program and when a position is found in the CAT database it will use the information enabling the engine to compute one ply deeper in most cases.  Other features of CAT include automatic learning, import of positions and analysis from several chess programs to compare results to better determine which was the best move generated.   The CAT feature alone is worth the cost of Rebel!

Apart from the above Rebel is supplied with a database of games which has been increased with this release by 300,000 games to total 800,000 high quality games!

The Openings book has been expanded with an extra 60,000 new book moves concerning latest opening theory.  Now with 46,000 variations the book references some 2.6 million unique positions.

Ed has managed to find something in the region of +100 elo improvement in Computer v Computer games.   This is bourne out by the testing I have done against the other top programs currently on the market.   Elo of +100 equates to approx. +20 to +30 elo against human opposition.

Hash table persistency has now been incorporated.  This helps where calculated search results are stored in hash ram for future use on successive moves.  The search algorithm has also been speeded up.

Other interesting facilities, begging to be investigated are, Bluff Chess, Tactical Engine and Club Player.

One of the most interesting facilities is the personality change.  Various parameters have been tapped into by the programmer and allow the user to vary some of the critical criteria that the program uses to decide the way in which the game will be played.  A separate utility is built to set new personalities, but they can also be set directly within Rebel, and saved with a unique name for later recall.

I suspect we have not heard the last of the personalities facility.  Rebel was set to what was thought to be the strongest personality setting, but extended parameter experimentation/testing has revealed small improvements on the default engine.  This suggests that there is room for the owner to experiment and perhaps find a stronger version of Rebel within the personality changes.  Perhaps there is another +100 elo to be found by experimentation.  Who knows?  The benefit is the fun in experimenting and testing.


This is the second major release of Chess Tiger under it's new Chess Partner interface (at version 5.0 now).  The GUI environment has been enhanced considerably.  The menu options are now Windows/Office 2000 styled. Winboard engines are supported, and access to Chess Internet servers is available directly from the Interface.  Of particular note (though not a new facility) is the ability to add an infinite number of new levels to the existing mechanism.  The owner has the ability to define their own tailored levels and name them for seamless incorporation into the default levels listbox, a very neat facility.

A version of Rebel is now available and can be switched into Tiger for analysis only!

Hash Ram assignment for Tiger has been improved.  Set the maximum available for the system and let Tiger assign the necessary ram according to the level of play set.  Much more civilised.

Tiger now shows pondering during the opponents thinking time.  This is a good improvement for Tiger owners as the more information feedback that can be presented the more interesting each game becomes.

This new release of Tiger makes it possibly the strongest single processor chess program on the market at the time of release.  All the top programs are much closer in strength now than in years gone by.  Therefore a considerable number of games is required at a variety of time controls in order to determine which programs have the advantage in various areas of the game.  It is becoming increasingly more difficult to say that one specific program is overall strongest in all areas of play.  My prediction is that Tiger will be at the top, or at worst in the first three.  With Gambit Tiger (see below) perhaps not that far behind.

During the beta test phase Christophe Theron released a slight change to the Tiger program for the testers to experiment with.  It was supplied with the note, not quite as strong but a different approach.  Suddenly reports came in from Beta testers of a revelation in chess playing ability.  All games of this changed engine were exciting, cavalier, edge of the seat stuff.  As more and more reports came in of its abilities Christophe decided to release the engine in its own right, and due to the nature of the reports coming in the new engine was given the title Gambit Tiger.  It appears to be slightly more careless in it's play sometimes in comparison with Chess Tiger but this has not deterred it from winning two tournaments and creating a lot of discussion about a new direction in Computer Chess.

In the main chess writers looked to build the strongest engines they could produce regardless of how sedate the programs play was, suddenly Gambit was showing a new approach (it had been thought about by others but never really successfully implemented), a new exciting, attacking, cavalier style.  Who cared if it lost the odd game here and there, the games were never dull.

Christophe may have set a new trend or direction for the rest of the marketplace to follow, or be left behind in the race.

Not only should a program play excellent chess, if the program can play in an exciting and cavalier manner this has to be a crowd puller, and better for chess in general.  It should see more converts wanting to jump on the bang wagon and experience this new style of play, for a chess computer.

My prediction is that Christophe has opened up a new direction for chess programming in general.  The chess marketplace must follow suit or fall by the wayside.

Interestingly Rebel has this capacity built in to alter certain parameters of the program to suit a more cavalier style of play.

The Rebel camp are ahead of the game.

Who will be the first to catch up?

Keith Kitson