An alternate arrangement is the reverse of the one shown here, with the
home board on the left and the outer board on the right.
This manual describes how to use GNU Backgammon to play and analyse backgammon games and matches. It corresponds to version 0.11 (updated in April, 2001).
GNU Backgammon (gnubg) plays and analyses backgammon games and matches.
It is currently a work-in-progress. So far it is able to play individual games and tournament matches, evaluate and roll out positions, tune its own evaluation functions using either TD or supervised training, maintain databases of positions for training and other purposes, and more.
It is driven by a command-line interface, and displays an ASCII rendition of a board on text-only terminals, but also allows the user to play games and manipulate positions with a GTK+ board window where available. It is extensible on platforms which support Guile.
It currently plays at about the level of a championship flight tournament player (depending on its parameters and its luck in recent games, it rates from around 1900 to 2000 on FIBS, the First Internet Backgammon Server -- at its strongest, it ranks in the top 5 of over 6000 rated players there) and is gradually improving; it should be somewhat stronger than this when released. Since almost all of the CPU time required during supervised training is spent performing rollouts, and rollouts can easily be performed in parallel, it is hoped that users will be able to pool rollout results and collectively train it to a level stronger than any individual could obtain.
If you can tolerate the rough edges, periodic pre-releases of the source will be made on the alpha.gnu.org FTP server.
Anonymous CVS access to the very latest code is available: if you have a
CVS client, set CVSROOT to
:pserver:[email protected]:/cvs and check out module
gnubg. If not, daily snapshots of the CVS repository are made
available by FTP, or you
can browse the repository through the
WWW gateway. Do
not expect this code to be stable; it will generally include both more
features and more bugs than the main pre-release version.
You can also compete against recent versions of gnubg on FIBS; it
plays there under the names gnu, mgnutest, mpgnu
and gnu_one_ply.
The rules presented in this chapter were written by Tom Keith for the Backgammon Galore web site, and are included here with his permission.
Backgammon is a game for two players, played on a board consisting of twenty-four narrow triangles called points. The triangles alternate in color and are grouped into four quadrants of six triangles each. The quadrants are referred to as a player's home board and outer board, and the opponent's home board and outer board. The home and outer boards are separated from each other by a ridge down the center of the board called the bar.
| | Figure 1. A board with the checkers
in their initial position.
An alternate arrangement is the reverse of the one shown here, with the
home board on the left and the outer board on the right.
|
The points are numbered for either player starting in that player's home board. The outermost point is the twenty-four point, which is also the opponent's one point. Each player has fifteen checkers of his own color. The initial arrangement of checkers is: two on each player's twenty-four point, five on each player's thirteen point, three on each player's eight point, and five on each player's six point.
Both players have their own pair of dice and a dice cup used for shaking. A doubling cube, with the numerals 2, 4, 8, 16, 32, and 64 on its faces, is used to keep track of the current stake of the game.
The object of the game is for a player to move all of his checkers into his own home board and then bear them off. The first player to bear off all of his checkers wins the game.
 | Figure 2. Direction of movement of
White's checkers. Red's checkers move in the opposite direction.
|
To start the game, each player throws a single die. This determines both the player to go first and the numbers to be played. If equal numbers come up, then both players roll again until they roll different numbers. The player throwing the higher number now moves his checkers according to the numbers showing on both dice. After the first roll, the players throw two dice and alternate turns.
The roll of the dice indicates how many points, or pips, the player is to move his checkers. The checkers are always moved forward, to a lower-numbered point. The following rules apply:
 | Figure 3. Two ways that White can
play a roll of 53.
|
A point occupied by a single checker of either color is called a blot. If an opposing checker lands on a blot, the blot is hit and placed on the bar.
Any time a player has one or more checkers on the bar, his first obligation is to enter those checker(s) into the opposing home board. A checker is entered by moving it to an open point corresponding to one of the numbers on the rolled dice.
For example, if a player rolls 4 and 6, he may enter a checker onto either the opponent's four point or six point, so long as the prospective point is not occupied by two or more of the opponent's checkers.
 | Figure 4. If White rolls 64 with a
checker on the bar, he must enter the checker onto Red's four point
since Red's six point is not open.
|
If neither of the points is open, the player loses his turn. If a player is able to enter some but not all of his checkers, he must enter as many as he can and then forfeit the remainder of his turn.
After the last of a player's checkers has been entered, any unused numbers on the dice must be played, by moving either the checker that was entered or a different checker.
Once a player has moved all of his fifteen checkers into his home board, he may commence bearing off. A player bears off a checker by rolling a number that corresponds to the point on which the checker resides, and then removing that checker from the board. Thus, rolling a 6 permits the player to remove a checker from the six point.
If there is no checker on the point indicated by the roll, the player must make a legal move using a checker on a higher-numbered point. If there are no checkers on higher-numbered points, the player is permitted (and required) to remove a checker from the highest point on which one of his checkers resides. A player is under no obligation to bear off if he can make an otherwise legal move.
 | Figure 5. White rolls 64 and bears
off two checkers.
|
A player must have all of his active checkers in his home board in order to bear off. If a checker is hit during the bear-off process, the player must bring that checker back to his home board before continuing to bear off. The first player to bear off all fifteen checkers wins the game.
Backgammon is played for an agreed stake per point. Each game starts at one point. During the course of the game, a player who feels he has a sufficient advantage may propose doubling the stakes. He may do this only at the start of his own turn and before he has rolled the dice.
A player who is offered a double may refuse, in which case he concedes the game and pays one point. Otherwise, he must accept the double and play on for the new higher stakes. A player who accepts a double becomes the owner of the cube and only he may make the next double.
Subsequent doubles in the same game are called redoubles. If a player refuses a redouble, he must pay the number of points that were at stake prior to the redouble. Otherwise, he becomes the new owner of the cube and the game continues at twice the previous stakes. There is no limit to the number of redoubles in a game.
At the end of the game, if the losing player has borne off at least one checker, he loses only the value showing on the doubling cube (one point, if there have been no doubles). However, if the loser has not borne off any of his checkers, he is gammoned and loses twice the value of the doubling cube. Or, worse, if the loser has not borne off any of his checkers and still has a checker on the bar or in the winner's home board, he is backgammoned and loses three times the value of the doubling cube.
The following optional rules are in widespread use.
When backgammon tournaments are held to determine an overall winner, the usual style of competition is match play. Competitors are paired off, and each pair plays a series of games to decide which player progresses to the next round of the tournament. This series of games is called a match.
Matches are played to a specified number of points. The first player to accumulate the required points wins the match. Points are awarded in the usual manner: one for a single game, two for a gammon, and three for a backgammon. The doubling cube is used, so the winner receives the value of the game multiplied by the final value of the doubling cube.
Matches are normally played using the Crawford rule. The Crawford rule states that if one player reaches a score one point short of the match, neither player may offer a double in the immediately following game. This one game without doubling is called the Crawford game. Once the Crawford game has been played, if the match has not yet been decided, the doubling cube is active again.
| Match to 5 | White | Black | |||
 | |||||
| Game 1: | White wins 2 points | 2 | 0 |  | Doubling Allowed |
| Game 2: | Black wins 1 point | 2 | 1 | ||
| Game 3: | White wins 2 points | 4 | 1 | ||
| Game 4: | Black wins 1 point | 4 | 2 | Crawford Game | |
| Game 5: | Black wins 2 points | 4 | 4 |  | Doubling Allowed |
| Game 6: | White wins 2 points | 6 | 4 | ||
| |||||
In this example, White and Black are playing a 5-point match. After three games White has 4 points, which is just one point short of what he needs. That triggers the Crawford rule which says there can be no doubling in next game, Game 4.
There is no bonus for winning more than the required number of points in match play. The sole goal is to win the match, and the size of the victory doesn't matter.
Automatic doubles, beavers, and the Jacoby rule are not used in match play.
Although GNU Backgammon has many commands and options, only a few of them are used during routine play. This chapter demonstrates some of those most commonly used.
If your gnubg installation is complete, you should be able to start it and see output similar to the following:
GNU Backgammon 0.02 Copyright 1999, 2000, 2001 Gary Wong. GNU Backgammon is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GNU Backgammon. Type "show warranty" for details. (No game)
When you start a game, gnubg will (by default) show which player's move it
is; it is displaying (No game) at the moment to indicate that it
isn't anybody's turn.
GNU Backgammon uses a pseudo-random number generator to produce dice rolls. It will normally initialise the state of the generator to some value based on the current time (and perhaps other system information, depending what features are available on your platform). But for purposes of this example, it will be better to start the generator from a known state, so that the rolls it generates will be repeatable. Enter the following command to change the generator state ("seed"):
(No game) set seed 15 Seed set to 15. (No game)
The default settings allow you to play X (the black pieces, if you have a graphical board window) and the computer will play O (red). It will play with no lookahead by default; it is very fast at choosing moves in this mode (instantaneous, on most hardware) though it does not play at its full strength. Let's start a game.
(No game) new game gnubg rolls 1, user rolls 3. GNU Backgammon Position ID: 4HPwATDgc/ABMA +13-14-15-16-17-18------19-20-21-22-23-24-+ gnubg | X O | | O X | | X O | | O X | | X O | | O | | X | | O | | X | | O | v| |BAR| | (Cube: 1) | O | | X | | O | | X | | O X | | X | | O X | | X O | | O X | | X O | Rolled 13 +12-11-10--9--8--7-------6--5--4--3--2--1-+ user (user)
This is the output you will see if a graphical board is unavailable or disabled; if your environment supports a graphical board, you will see a better representation of a backgammon board than this. Exactly the same information is available, either way.
You have just won the opening roll (you have a 3, and gnubg has a 1) -- the
dice roll is in the bottom right hand corner for the TTY board, or shown
as graphical dice on the right hand side of the board window. The
position ID (the 4HPwATDgc/ABMA in this example) is an encoded
representation of the current position. It comes in useful when using
some of gnubg's advanced commands, but you can safely ignore it for now.
Notice that the prompt has changed to (user), to indicate that it
is your turn; on systems where a login name is available, gnubg will
use that instead.
If you are familiar with backgammon, you will know that the best play for this roll is to make your 5 point. The command to do that is:
(user) 8 5 6 5
in the terminal window (i.e. move one chequer from your 8 point to your 5 point, and move another from your 6 to your 5 point); or by dragging each chequer to the destination point in the board window. Click mouse button 1 on the dice to indicate you have finished your move (just as you would pick up your dice to end your move if you were playing on a real board).
Once you have done that, gnubg will take its turn, rolling 63 and playing 24/15. It is now your move again:
GNU Backgammon Position ID: 4HPwCSCwZ/ABMA +13-14-15-16-17-18------19-20-21-22-23-24-+ gnubg | X O | | O X | | X O | | O X | | X O | | O | | X | | O | | X | | O | v| |BAR| | (Cube: 1) | O | | | | O | | X | | O | | X | | O X | | X X | | O O X | | X X O | On roll +12-11-10--9--8--7-------6--5--4--3--2--1-+ user (user)
Since it is no longer the opening roll, you have the option of doubling before rolling your dice. To roll without doubling, just enter the command roll (or r for short):
(gnubg) roll GNU Backgammon Position ID: 4HPwCSCwZ/ABMA +13-14-15-16-17-18------19-20-21-22-23-24-+ gnubg | X O | | O X | | X O | | O X | | X O | | O | | X | | O | | X | | O | v| |BAR| | (Cube: 1) | O | | | | O | | X | | O | | X | | O X | | X X | | O O X | | X X O | Rolled 35 +12-11-10--9--8--7-------6--5--4--3--2--1-+ user (user)
(You can also roll by clicking the dice just underneath the board window.)
Let's play this roll by hitting twice: 13/10*, 6/1*. You can enter this move with 13 10 6 1 -- note that you don't need to specify anything special to hit; gnubg will automatically move blots that are hit to the bar. You can also make this move by dragging chequers in the board window, of course.
(user) 13 10 6 1 GNU Backgammon Position ID: 4HPwAWBhZ+IBMA +13-14-15-16-17-18------19-20-21-22-23-24-+ gnubg | X O | O | O X | | X O | O | O X | | X O | | O | | X | | O | | | | O | v| |BAR| | (Cube: 1) | O | | | | O | | | | O | | X | | O X | | X X | | O X X | | X X X | On roll +12-11-10--9--8--7-------6--5--4--3--2--1-+ user (user)
GNU Backgammon has rolled 65 and been unable to move. Let's take another roll:
(user) roll GNU Backgammon Position ID: 4HPwAWBhZ+IBMA +13-14-15-16-17-18------19-20-21-22-23-24-+ gnubg | X O | O | O X | | X O | O | O X | | X O | | O | | X | | O | | | | O | v| |BAR| | (Cube: 1) | O | | | | O | | | | O | | X | | O X | | X X | | O X X | | X X X | Rolled 25 +12-11-10--9--8--7-------6--5--4--3--2--1-+ user (user)
Play this roll as 13 11 6 1. gnubg will now roll 16 -- and still can't move!
GNU Backgammon Position ID: 4HPwAWDDZsoBMA +13-14-15-16-17-18------19-20-21-22-23-24-+ gnubg | X O | O | O X | | X O | O | O X | | X O | | O | | | | O | | | | O | v| |BAR| | (Cube: 1) | O | | | | O | | | | O | | | | O X | | X X X | | O X X X | | X X X | On roll +12-11-10--9--8--7-------6--5--4--3--2--1-+ user (user)
Our position is now strong. Let's try doubling -- this can be done by entering the command double at the prompt, or by clicking the doubling cube in the board window. When you are doubled, you should use the command take or drop to accept or refuse the cube. GNU Backgammon will drop this double:
(user) double gnubg refuses the cube and gives up 1 point. user wins a single game and 1 points. The score (after 1 game) is: gnubg 0, user 1 (money session, without Jacoby rule).
That concludes the example game. You have seen most of the commands normally used while playing; others you will need include bar when re-entering a hit chequer (e.g. bar 20 24 20) and off to remove a chequer from the board when bearing off (e.g. 6 off 5 off).
Type help from within gnubg for a summary of all commands, or browse the rest of this manual to learn more. Have fun playing GNU Backgammon!
This chapter describes how to run gnubg, and how to end it when you are finished.
Start GNU Backgammon by running the program gnubg. Once started, it will process commands from the terminal.
You can also instruct gnubg to read an existing game or match from a file, to play or analyse. To read from filename, specify gnubg filename.
gnubg will give you a short summary of how to invoke it if given the
option --help (-h for short), and report its version
with --version (-v).
GNU Backgammon will normally use a graphical board window if a window
system is available. To prevent this behaviour and use standard
terminal output instead, you can specify the --tty option (which
can be abbreviated to -t).
By default, gnubg will attempt to load pre-trained neural net
weights; if you have no weights or wish to train a net from scratch,
you can supply the --no-weights (-n) option, and
new weights will be randomly generated.
FIXME the previous command is out of date; -no-weights is now -new-weights.
FIXME document -no-bearoff, -no-rc, -datadir and -window-system-only options.
exit
quit
gnubg will also exit upon end-of-file; you can therefore exit by typing an end-of-file character (usually C-d, i.e. hold the <CTRL> key and press D).
If you send an interrupt sequence (often by pressing C-c), the current gnubg command (if any) will be terminated. This can be useful if you do not want to wait for a slow command to complete.
You can execute shell commands from gnubg without leaving or suspending it.
![command]
SHELL if it is set, or defaults to /bin/sh if not).
There are a few simple commands you can use within GNU Backgammon to display information you might need to know:
help [command]
? [command]
help by itself
lists the main commands with a one-line description of each; when
command is specified, that command is explained in more detail,
and if it has any subcommands then they are listed in brief.
? is a synonym for help.
show copying
show warranty
show copying and show warranty commands, or see the file
COPYING in the gnubg distribution (the contents are identical).
This chapter introduces several more commands used while playing games and matches in gnubg.
new game
new game
will set up the board in the starting position, and roll one die for
each player for the opening move.
If you are in the middle of a game, new game will ask you if
you want to abort the game in progress. If you do, a new game will
replace the current one (i.e. the partially completed game will have
no effect on the score). If you want the current game to be scored
for either player, you should use the resign command instead.
move from to ...
move =number
from to ...
=number
move command allows you to make chequer plays when it is your
turn. In its normal form, you should specify pairs of point numbers
indicating the points you want to move a chequer from and to. Specify
one pair for each chequer you want to move. (For instance, on an
opening roll of 31, you might use move 8 5 6 5 to move two
chequers -- one from your 8 point to your 5 point, and the other from
your 6 point to your 5 point.) For several example moves, see
Sample Game.
You should use the words bar and off when moving a chequer
from the bar or bearing it off the board, e.g. move bar 20 or
move 3 off. These words can be abbreviated to b and
o respectively.
If there is only one legal move you can make, then the command move
by itself will make it for you without requiring you to specify it in full.
Similarly, if there is no play available at all, then move will
end your turn without moving.
As long as you specify at least one pair of points, then the word
move is optional -- the command bar 20 24 20 means exactly
the same thing as move bar 20 24 20, for instance.
FIXME document `=n' notation.
If you are using a window system, you can also move chequers using the board window. One way to do this is to use any mouse button to drag a chequer (that is, press the button when the pointer is over the chequer you wish to move; move the pointer to the point you wish to play it to, and then release the button).
An alternative is to click a mouse button on the chequer; button 1 will move it by the number of pips showing on the left die, and any other button will move it according to the right die. If you don't like the order the dice are displayed in, pressing either button 2 or 3 on the dice will swap their positions.
Whichever method you use to move the chequers, once you have made a legal move you can end your turn by clicking mouse button 1 on the dice.
FIXME reference set auto move and set auto bearoff.
resign [type]
agree
accept
decline
reject
resign command is used to give up a game without playing it to
completion. It is often useful during endgame play when the game reaches
a position where it is impossible for one player to win. If you do not
specify a value type, then the player whose turn it is offers to
give up one game (at the current cube value) to the opponent; you can
also specify 1, 2 or 3 to resign a single, double
or triple game. Specifying normal, gammon or
backgammon is also legal, and is identical to expressing the
number of points as a digit. single is yet another synonym for
one game.
The opponent may accept the resignation with either the agree or
accept commands, but is not obliged to. To ignore the
resignation and continue play normally, use either the decline or
reject commands. (accept and reject are also legal
commands in response to a double; see Cube.)
set board id|=number
set board command. You need to know the
position ID of the chequer arrangement you want; position IDs
are always displayed when the board is shown. (If you are playing
on a text terminal, the position ID is in the upper right hand corner
of the board diagram; when using the board window, the ID is shown
below the board on the right hand side.) For instance, to set the
chequers to the starting position, use the command
set board 4HPwATDgc/ABMA.
FIXME reference =n notation and describe the GTK edit mode
show board [id|=number]
show board command is used to display a particular position --
normally the board of the current game, but it is also possible to view
unrelated layouts. When specified without the optional id parameter,
the current position is displayed. (When using a text terminal, this
is useful if subsequent output has caused the board diagram to scroll
off the screen. In the board window, the command can be used to undo
erroneous chequer plays by resetting the window to the position at the
start of the turn.)
When a position ID id is given, the chequers are arranged into
the position specified and that board is displayed. Note that this
command affects the display only; the current game is unchanged. Use
the show board command with no parameter if you want to see
the current game again.
hint
hint command to see the moves gnubg recommends.
The output is of the following form:
Win W(g) W(bg) L(g) L(bg) Equity Move 0.542 0.142 0.008 0.113 0.008 (+0.114) 6/5 8/5 0.505 0.120 0.008 0.122 0.007 (+0.009) 24/23 23/20 0.498 0.126 0.008 0.123 0.007 (+0.000) 24/23 13/10 0.499 0.113 0.008 0.121 0.007 (-0.011) 24/23 24/21 0.486 0.125 0.008 0.120 0.009 (-0.024) 13/10 10/9 0.481 0.116 0.008 0.129 0.008 (-0.051) 6/5 24/21 0.472 0.122 0.008 0.129 0.009 (-0.064) 6/5 13/10
The moves are listed in descending order of preference, so in this case,
gnubg recommends the move 6/5 8/5. The first five columns are
its estimates of the probability of the player on roll winning
(Win), winning a gammon (W(g)), winning a backgammon
(W(bg)), losing a gammon (L(g)), and losing a backgammon
(L(bg)) if the game is played to completion without use of the
doubling cube, after the candidate move in that row is
made1. The sixth column,
Equity, is the estimated cubeless equity following the move --
this is the expected number of points per game won by the player on
roll.
FIXME describe =n notation.
gnubg will `look ahead' a certain number of moves when evaluating
the probabilities, according to the search depth set by the
set plies command (see Analysis).
show pipcount [id|=number]
show pipcount to automatically count the number of `pips'
each player needs to bear off. Depending on the position, the output
will look something like:
The pip counts are: X 103, O 112.
show player
set player name human
set player old-name name new-name
show player to summarise these settings. By default,
gnubg will play for player 0, whose name is initially gnubg.
Player 1 defaults to a human (i.e. gnubg will prompt the user
for a move when it is player 1's turn) whose name is the user's login
name, on systems where this information is available; on single-user
systems, the default name user applies.
Either player can be set to a human with the command set player
name human, where name is either the number of the player
(0 or 1) or that player's name (initially gnubg and user
or the user's login name). You can also specify both which will
set both players simultaneously. There are also options for computer
players (see Computer Player).
You can change the names of the players with the
set player old-name name new-name command. Again,
either the player numbers or names are valid for the old-name
parameter. Names may not contain whitespace characters, and may not
be longer than 31 characters. The names 0, 1 and
both are not permitted, to avoid ambiguities, and the players
may not both share the same name. Names are not case sensitive.
set turn player
show turn
set turn player (where player can be the
player's name or number, as above) is used to control which player is on
roll. It will cancel the current dice roll and cube action (if any),
and set the named player on roll.
set automatic bearoff
set automatic move
set display value
The command set display off will suppress this output, which can
speed up the display and reduce clutter (this might be useful when completing
a game where both sides are played by the computer, for instance).
set display on will restore the default behaviour. The standard
toggle synonyms may be substituted for on and off.
The board will always be updated when it is a human player's turn to move,
regardless of the display setting.
roll
set automatic roll value
set automatic roll command
instructs gnubg to go ahead and roll the dice without waiting for the
player to issue roll, whenever no doubling decision is necessary.
The standard toggle commands may be used to turn this option on and off.
set dice pips pips
set dice command. The player can then play a move
according to the dice specified. Like the roll command, this will
also forego any opportunity to double; to disregard a dice roll and
allow the player to roll again (or double, if permitted), use set
turn player.
set rng generator [seed]
show rng
The set rng command is used to select which generator will be used.
The generator parameter must be one of the following:
ansi
rand() random number generator. The
behaviour of this generator will depend on the C library linked with
gnubg, but is typically a linear congruential pseudo-random number
generator. Such generators have fairly weak distribution properties,
but are generally adequate for producing backgammon dice. However, the
ANSI generator is not recommended for performing rollouts, because any
small biases in the dice could accumulate over hundreds or thousands of
trials and distort the results. Using a better generator would be
safer for rollouts.
bsd
random() non-linear additive feedback random number
generator. This is a good quality generator, but is not available on
all systems. gnubg will report an error if you attempt to use this
generator if the C library used in your installation does not include
the BSD random code.
isaac
manual
manual, gnubg will not generate
the dice itself; rather, it will prompt for a roll to be entered whenever
one is required.
md5
n+1 will be identical to that generated by seed n,
with the first roll omitted. The command show seed is available
when using the md5 generator, for obtaining the current seed value.
mersenne
user
user generator to dynamically load a user library which
will be used to produce the dice rolls. See the file userrng.c
in the gnubg distribution for an example user generator, and instructions
on how to write your own.
set seed seed
set seed command. FIXME
show seed
set player name gnubg
set player name pubeval
pubeval. This will cause moves for that player to be made by
Gerry Tesauro's benchmark player. pubeval is much weaker than
gnubg's own evaluator, but provides a constant level of play which
is useful for measuring different players against.
pubeval is not capable of making cube or resignation decisions
based on the position. It will never accept resignations at less than
triple (backgammon) stakes, and will take all cubes. It nevers offers
resignations or doubles of its own.
set player name external
set player name evaluation
play
external
This section describes how to use GNU Backgammon to play series of games, whether those games are part of a match (as in tournament backgammon) or a session of independent games (conventionally called "money" play, regardless of whether any payment is involved).
new match length
new session
set automatic game
set crawford
set postcrawford
set automatic crawford
set jacoby
set automatic doubles limit
set score points points
show crawford
show postcrawford
show jacoby
show score
double
redouble
beaver
take
accept
drop
pass
reject
set cube centre
set cube owner player
set cube use
set cube value points
save game file
save match file
load game file
load match file
set colours
set delay
show delay
eval [id|=number]
rollout [id|=number ...]
set evaluation
set rollout
set cache size
show cache
show gammonprice
show marketwindow
show matchequitytable
analysis
database dump
database export
export database
database generate
database import
import database
database rollout
database train
train database
new weights
save weights file
load weights file
database train
train database
train td
:
Pre-release snapshots of GNU Backgammon are periodically made available for FTP at ftp://alpha.gnu.org/gnu/gnubg/.
If you want to experiment with the very latest code, the development
sources are kept in a CVS repository at
http://subversions.gnu.org/cgi-bin/cvsweb/gnubg/; see the gnubg
web page at http://www.gnu.org/software/gnubg/gnubg.html for
instructions on checking out sources from the repository. Daily snapshots of
the main branch of the repository are automatically placed in the
snapshots directory of the FTP area above, if you wish to retrieve
this experimental code via FTP.
Once you are running gnubg, enter new game at the
(gnubg) prompt to start a game against the computer opponent.
You should now see a board (if a window system is available, gnubg
will use a graphical board window; otherwise, it will display an ASCII
board on your terminal). If gnubg won the opening roll, it will have
moved; you can now type roll (or click on the dice below the board
window) to roll the dice yourself. In either case, it will now be your
move; you should enter the moves for each chequer as pairs of numbers.
For instance, if you have rolled 3 and 1, you could type 8 5 6 5
to move one chequer from the 8 point to the 5 point and another from the
6 point to the 5 point. Use bar to move from the bar, and
off to bear off. If you are using the board window, you can also
drag chequers around the board. Click on the dice when you have
finished.
gnubg.bd: No such file or directory. What's wrong?The file gnubg.bd is the bearoff database that gnubg uses to
evaluate endgame positions. gnubg will look for it first in the current
directory and then in the installed directory (/usr/local/share/gnubg/
by default).
The gnubg distribution is set up to create gnubg.bd by itself
during compilation, but it can be a slow process (taking half an hour
or more, depending on the speed of your computer). If you would rather
not wait to generate the database yourself, you can obtain a copy
via FTP from ftp://alpha.gnu.org/gnu/gnubg/gnubg.bd.gz.
FIXME this is out of date; gnubg can cope without gnubg.bd if it has to.
gnubg.weights: No such file or directory. What's that?The file gnubg.weights contains the trained neural net weights
for most of gnubg's position evaluators. Like gnubg.bd, it should
be kept in either the current directory or the installed directory.
A binary variant of the weights file named gnubg.wd can also be
used (this version can be loaded more quickly, but is not portable
between different computer architectures). It will automatically be
built during the compilation process, and used in preference to
gnubg.weights if found.
You should be able to obtain a copy of the weights from wherever you
found the gnubg distribution. If you wish to start gnubg without
any weights (and train your own), you can use the --no-weights
option (see see Invoking gnubg).
If you see this problem, your X server is probably using a PseudoColor visual, and is dynamically allocating colours to clients from a limited colourmap. On these types of displays, gnubg tries to be a well-behaved client by using colours from the default standard colourmap. This will allow it to share colours with other clients that use the same scheme, which will help them all to use as many colours as possible without exhausting the colourmap.
Unfortunately, not all X clients use standard colourmaps. If other
clients have been run before gnubg and allocated most of the colours,
then there may not be enough left for gnubg to allocate a standard
colourmap. If this happens, it will just take what it can get (which
in the worst case might be black and white only). You can try to
avoid this problem by running gnubg before other colour-hungry clients,
or by using the xstdcmap utility to install the default
standard colourmap early in your session while colours are still
available. Depending on your hardware, you may be able to configure
your display to allow more colours, or use a DirectColor or
TrueColor visual which should resolve the problem.
Of course, if your X server can only display black and white (not even shades of grey), then there's not much you can do!
Version 1.1, March 2000
Copyright (C) 2000 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The purpose of this License is to make a manual, textbook, or other written document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software. We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.
This License applies to any manual or other work that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language. A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (For example, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them. The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, whose contents can be viewed and edited directly and straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup has been designed to thwart or discourage subsequent modification by readers is not Transparent. A copy that is not "Transparent" is called "Opaque". Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML designed for human modification. Opaque formats include PostScript, PDF, proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML produced by some word processors for output purposes only. The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text.
You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3. You may also lend copies, under the same conditions stated above, and you may publicly display copies.
If you publish printed copies of the Document numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects. If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages. If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a publicly-accessible computer-network location containing a complete Transparent copy of the Document, free of added material, which the general network-using public has access to download anonymously at no charge using public-standard network protocols. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.
You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice. The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work. In the combination, you must combine any sections entitled "History" in the various original documents, forming one section entitled "History"; likewise combine any sections entitled "Acknowledgements", and any sections entitled "Dedications". You must delete all sections entitled "Endorsements."
You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects. You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.
A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, does not as a whole count as a Modified Version of the Document, provided no compilation copyright is claimed for the compilation. Such a compilation is called an "aggregate", and this License does not apply to the other self-contained works thus compiled with the Document, on account of their being thus compiled, if they are not themselves derivative works of the Document. If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one quarter of the entire aggregate, the Document's Cover Texts may be placed on covers that surround only the Document within the aggregate. Otherwise they must appear on covers around the whole aggregate.
Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License provided that you also include the original English version of this License. In case of a disagreement between the translation and the original English version of this License, the original English version will prevail.
You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/. Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.
To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A copy of the license is included in the section entitled "GNU Free Documentation License".If you have no Invariant Sections, write "with no Invariant Sections" instead of saying which ones are invariant. If you have no Front-Cover Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise for Back-Cover Texts. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.
accept: Cube
accept: The Game
agree: The Game
analysis: Analysis
beaver: Cube
:: Guile
!: Shell Commands
?: Basic Commands
database dump: Databases
database export: Databases
database generate: Databases
database import: Databases
database rollout: Databases
database train: Training
database train: Databases
decline: The Game
double: Cube
drop: Cube
eval: Analysis
exit: Leaving gnubg
export database: Databases
external: Computer Player
help: Basic Commands
hint: The Game
import database: Databases
load game: Recording
load match: Recording
load weights: Training
move: The Game
new game: The Game
new match: Matches and Sessions
new session: Matches and Sessions
new weights: Training
pass: Cube
play: Computer Player
quit: Leaving gnubg
redouble: Cube
reject: Cube
reject: The Game
resign: The Game
roll: Dice
rollout: Analysis
save game: Recording
save match: Recording
save weights: Training
set automatic bearoff: The Game
set automatic crawford: Matches and Sessions
set automatic doubles: Matches and Sessions
set automatic game: Matches and Sessions
set automatic move: The Game
set automatic roll: Dice
set board: The Game
set cache: Analysis
set colours: GTK
set crawford: Matches and Sessions
set cube centre: Cube
set cube owner: Cube
set cube use: Cube
set cube value: Cube
set delay: GTK
set dice: Dice
set display: The Game
set evaluation: Analysis
set jacoby: Matches and Sessions
set player evaluation: Computer Player
set player external: Computer Player
set player gnubg: Computer Player
set player human: The Game
set player name: The Game
set player pubeval: Computer Player
set postcrawford: Matches and Sessions
set rng: Dice
set rollout: Analysis
set score: Matches and Sessions
set seed: Dice
set turn: The Game
show board: The Game
show cache: Analysis
show copying: Basic Commands
show crawford: Matches and Sessions
show delay: GTK
show gammonprice: Analysis
show jacoby: Matches and Sessions
show marketwindow: Analysis
show matchequitytable: Analysis
show pipcount: The Game
show player: The Game
show postcrawford: Matches and Sessions
show rng: Dice
show score: Matches and Sessions
show seed: Dice
show turn: The Game
show warranty: Basic Commands
take: Cube
train database: Training
train td: Training
gnubg.bd: gnubg.bd errors
gnubg.weights: gnubg.weights errors
Note that the probability of winning includes the probability of winning a gammon or backgammon, and likewise the gammon probabilities include the backgammon probabilities.