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Bill Angel ((email removed contact us for address) s.cais.com) adapted the GNU chess program to play Capablanca's chess, (a chess variant on an enlarged board with two new types of pieces). Below, you find the message he wrote explaining the variant and how to utilize his computer program that plays it. This program runs under DOS. The program.


A GNU CHESS Implementation of the Capablanca Deviation

What is the "Capablanca Deviation"?

Jose Raul Capablanca (1888-1942) was a Cuban chess master who suggested,starting in 1925, certain changes to the game primarily to make it less "bookish" and less likely for play to end in draws. He published an interview/article in 1929 (discussed in the book "Capablanca" by Edward Winter) an excerpt from which is presented below. He states that his objective is
...to introduce in the game new forces which would necessarily throw the players on to their own resources, and give much greater scope to the imagination and to the creative power of the individual player.
My own suggestions involve the introduction of new pieces upon the board: the Chancellor, combining the moves of the bishop and knight; and the Marshall combining the moves of the rook and the knight. This means to say that the Chancellor may be used either as a bishop or a knight for any move according to the will of the player, while the Marshall in the same way can be used as a rook or a knight. The introduction of the two pieces would of course mean a [larger] board and two extra pieces on each side. But it would not entail any alteration of the rules.
The great advantage which this proposal has....is that it infinitely increases the chances of sacrificial combinations; that it tremendously multiplies the few mysteries left in chess....thus making the game once more... a pastime in which there is always something to be learned and in which not memory only but foresight, imagination, resourcefulness are in constant demand. [end of excerpt]
To accommodate the new pieces this GNU Chess implementation has 10 columns, but still just 8 rows. The Chancellor was placed between the queen and its bishop, the Marshall between the king and its bishop.

Invoking the program

Type "CAPAGNU" and wait.... it takes about 30 sec on the basic IBM PC for the program to initialize itself.

The output of the program is in the form of ANSI standard graphics commands. This means that the line "device = ansi.sys" has to be present in the DOS config.sys file.

After entering, when asked, a timing selection, the board and pieces are displayed. At the prompt "Your move is?" typing "help" will invoke the help screen. This screen explains how to change parameters.

Some pointers:

If a pawn is to be promoted, type the promotion move followed by the choice of piece: a7a8q will promote the pawn to a queen, a7a8c will promote it to a chancellor.

The default search depth has been set to 6 ply. A larger value might be in order for an (80386) machine with a search time per move of 15 minutes or longer.

A search can be interrupted (the move forced) by typing some key (the space bar works well) while the computer search for a move is progressing.

The program can create and use a "persistent transposition table". To create it, first invoke the program with the "-t" option. The will produce a file "HASH.DAT", which is about 78 kbytes in size. Only for fast machines and/or really deep searches will it be used; it does not have to be created.

Capablanca Deviation Modifications to GNU Chess by:
William Angel
Internet: (email removed contact us for address) s.cais.com

Source code (in C) for this program is available. Please contact Bill Angel with any requests/comments.
WWW page created: 1995 or 1996. Last modified: February 16, 1996.