.TH Chess GNU
.SH NAME
Chess \- GNU Chess
.SH SYNOPSIS
.B Chess
[
.B arg1 arg2
]
.SH DESCRIPTION
.I Chess
plays a game of chess against the user or it plays against itself.
.PP
.I Chess
has a simple alpha-numeric board display or it can be compiled for
use with the CHESSTOOL program on a SUN workstation.
The program gets its opening moves from the file gnuchess.book which
should be located in the same directory as gnuchess.
To invoke the prgram, type 'gnuchess' or type 'chesstool gnuchess'
on a SUN workstation where 'CHESSTOOL' is installed.
The 'gnuchess' command can be followed by up to 2 command line arguments.
If one argument is given it determines the programs search time in
seconds.  If two arguments are given, they will be used to set tournament
time controls with the first argument being the number of moves and the second
being the total clock time in minutes.  Thus, entering 'chess 60 5' will set
the clocks for 5 minutes (300 seconds) for the first 60 moves.
If no argument is given the program will prompt the user for level of
play.
For use with CHESSTOOL, see the documentation on that program.
.PP
Once
.I Chess
is invoked, the program will display the board and prompt the user
for a move. To enter a move, use the notation 'e2e4' where the first
letter-number pair indicates the origination square
and the second letter-number pair indicates the destination square.
An alternative is to use the notation 'nf3' where
the first letter indicates the piece type (p,n,b,r,q,k).
To castle, type the origin and destination squares
of the king just as you would do for a regular move, or type
"o-o" for kingside castling and "o-o-o" for queenside.
.SH COMMANDS
.PP
In addition to legal moves, the following commands are available as responses.
.PP
.I beep
-- causes the program to beep after each move.
.PP
.I bd
-- updates the current board position on the display.
.PP
.I book
-- turns off use of the opening library.
.PP
.I both
-- causes the computer to play both sides of a chess game.
.PP
.I black
-- causes the computer to take the black pieces with the move
and begin searching.
.PP
.I level
-- allows the user to set time controls such as
60 moves in 5 minutes etc.  In tournament mode, the program will
vary the time it takes for each
move depending on the situation.  If easy mode is disabled (using
the 'easy' command), the program
will often respond with its move immediately, saving time on
its clock for use later on.
.PP
.I depth
-- allows the user to change the
search depth of the program.  The maximum depth is 29 ply.
Normally the depth is set to 29 and the computer terminates
its search based on elapsed time rather than depth.
Using the depth command allows setting depth to say
4 ply and setting response time to a large number such as
9999 seconds. The program will then search until all moves
have been examined to a depth of 4 ply (with extensions up
to 11 additional ply for sequences of checks and captures). 
.PP
.I easy
-- toggles easy mode (thinking on opponents time)
on and off. The default is easy mode ON.  If easy mode is disabled,
the user must enter a 'break' or '^C' to get the programs
attention before entering each move.
.PP
.I edit
-- allows the user to set up a board position.
In this mode, the '#' command will clear the board, the 'c'
command will toggle piece color, and the '.' command will exit
setup mode.  Pieces are entered by typing a letter (p,n,b,r,q,k) for
the piece followed by the coordinate.  For example "pb3" would
place a pawn on square b3.
.PP
.I force
-- allows the user to enter moves for both
sides. To get the program to play after a sequence of moves
has been entered use the 'white' or 'black' commands.
.PP
.I get
-- retrieves a game from disk.  The program will
prompt the user for a file name.
.PP
.I help
-- displays a short description of the commands.
.PP
.I hint
-- causes the program to supply the user with
its predicted move.
.PP
.I list
-- writes the game moves and some statistics
on search depth, nodes, and time to the file 'chess.lst'.
.PP
.I new
-- starts a new game.
.PP
.I post
-- causes the program to display the principle
variation and the score during the search.  A score of
100 is equivalent to a 1 pawn advantage for the computer.
.PP
.I random
-- causes the program to randomize its move
selection slightly.
.PP
.I reverse
-- causes the board display to be reversed.  That
is, the white pieces will now appear at the top of the board.
.PP
.I quit
-- exits the game.
.PP
.I save
-- saves a game to disk.  The program will prompt
the user for a file name.
.PP
.I switch
-- causes the program to switch places with
the opponent and begin searching.
.PP
.I undo
-- undoes the last move whether it was the computer's
or the human's. You may also type "remove". This is equivalent
to two "undo's" (e.g. retract one move for each side).
.PP
.I white
-- causes the computer to take the white pieces
with the move and begin searching.
.SH BUGS
.PP
Pawn promotion to pieces other than a queen is not allowed.
En-Passant does not work properly with CHESSTOOOL.
The transposition table may not work properly in some
positions so the default is to turn this off. 
.fi
.SH SEE ALSO
.nf
chesstool(6)
.fi