Backgammon rules
Backgammon is a simple game with deep strategic
elements. It does not take long to learn to play, although obscure
situations do arise which require careful interpretation of the rules.
Each player begins the game with fifteen checkers
of a different color from his opponent, a pair of dice, a dice cup, and a
doubling cube. Players move their checkers around the board according to the
roll of the dice. The first player to get all of his checkers, or men,
around and finally off the board is the winner.
The rules of backgammon are :
Hitting and
Entering Rule
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 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.
Doubling rule
Each face of the doubling cube
bears a number to record progressive doubles and redoubles, starting with 2
and going on to 4, 8, 16, 32 & 64. At the commencement of play, the doubling
cube rests on the bar, between the two players, or at the side of the board.
At any point during the game, a player who thinks he is sufficiently ahead
may, when it is his turn to play and before he casts his dice, propose to
double the stake by turning the cube to 2. His opponent may decline to
accept the double, in which case he forfeits the game and loses 1 unit, or
accept the double, in which case the game continues with the stake at 2
units. The player who accepts the double now ``owns'' the cube---which means
that he has the option t redouble at any point during the rest of the game,
but his opponent (the original doubler) may not. If, at a later stage he
exercises this option, his opponent is now faced with a similar choice. He
may either decline the redouble and so lose 2 units, or accept and play for
4, and he now ``owns'' the cube. A player may double when he is on the bar
even if his opponent has a closed board and he cannot enter. Though he does
not roll the dice, for he cannot make a move, he still has the right to
double. Note that gammon doubles or backgammon triples the stake of the
cube.
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.
Optional Rule
The following optional rules are in widespread use.
Automatic doubles. If identical numbers are thrown on the first roll, the
stakes are doubled. The doubling cube is turned to 2 and remains in the
middle. Players usually agree to limit the number of automatic doubles to
one per game.
Beavers. When a player is doubled, he may immediately redouble (beaver)
while retaining possession of the cube. The original doubler has the option
of accepting or refusing as with a normal double.
The Jacoby Rule. Gammons and backgammons count only as a single game if
neither player has offered a double during the course of the game. This rule
speeds up play by eliminating situations where a player avoids doubling so
he can play on for a gammon.
Bearing off rule
Once the program has finished loading you can
enter any backgame position provided the position not bearing off has 4 men
or less. The side bearing off can have from 1 to 15 men. The program will
return two probabilities: one for each side being on roll. These results are
the probabilities that the side bearing off will have a man hit.
After the probabilities are displayed, you are given a chance to find the
best move for the position you have just entered. Keep in mind that the best
move for the position bearing off is the one that leaves the other side with
the smallest probability of hitting a man. The best move for the side in the
backgame is the one that gives it the highest probability of hitting a man.
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 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.
2005
all right reserve
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