Backgammon

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Backgammon is a board game for two players in which the playing pieces are moved according to the roll of dice. A player wins by removing all of his checkers from the board. There are many variants of backgammon, most of which share common traits. Backgammon is a member of the tables family, one of the oldest classes of board games in the world.

Although luck plays an important role, there is a large scope for strategy. With each roll of the dice a player must choose from numerous options for moving his checkers and anticipate possible counter-moves by the opponent. Players may raise the stakes during the game. There is an established repertory of common tactics and occurrences.

Like chess, backgammon has been studied with great interest by computer scientists. Owing to this research, backgammon software has been developed capable of beating world-class human players.

History

game senet resembled backgammon, with moves controlled by the roll of dice. However, the Royal Game of Ur, played in ancient Mesopotamia, is a more likely ancestor of modern day tables games. Excavations at the "Burnt City" in Iran have shown that a similar game existed there around 3000 BC. The artifacts include two dice and 60 checkers, and the set is believed to be 100 to 200 years older than the sets found in Ur.

The ancient Romans played a number of games remarkably similar to backgammon. Ludus duodecim scriptorum ("Game of twelve lines") used a board with three rows of 12 points each, and the checkers were moved across all three rows according to the roll of dice. Little specific text about the gameplay has survived. Tabula, meaning "table" or "board", was a game mentioned in an epigram of Byzantine Emperor Zeno (AD 476–481). It was similar to modern backgammon in that the object of the game was to be the first to bear off all of one's checkers. Players threw three dice and moved their checkers in opposing directions on a board of 24 points.

In the 11th century Shahnameh, the Persian poet Ferdowsi credits Burzoe with the invention of the tables game nard in the 6th century. He describes an encounter between Burzoe and a Raja visiting from India. The Raja introduces the game of chess, and Burzoe demonstrates nard, played with dice made from ivory and teak. (Today, Nard is the name for the Persian version of backgammon, which has different initial positions and objectives.)

The jeux de tables (Game of Tables), predecessors of modern backgammon, first appeared in France during the 11th century and became a favorite pastime of gamblers. In 1254, Louis IX issued a decree prohibiting his court officials and subjects from playing.Tables games were played in Germany in the 12th century, and had reached Iceland by the 13th century. The Alfonso X manuscript Libro de los juegos, completed in 1283, describes rules for a number of dice and tables games in addition to its extensive discussion of chess.By the 17th century, tables games had spread to Sweden. A wooden board and checkers were recovered from the wreck of the Vasa among the belongings of the ship's officers. Backgammon appears widely in paintings of this period, mainly those of Dutch and German painters (Van Ostade, Jan Steen, Bosch and others). One surviving artwork is "Cardsharps" by Caravaggio (The backgammon board is in the lower left.) Others are the Hell of Bosch and interior of an Inn by Jan Steen.

In the 16th century, Elizabethan laws and church regulations prohibited playing tables, but by the 18th century backgammon was popular among the English clergy.[8] Edmund Hoyle published A Short Treatise on the Game of Back-Gammon in 1743; this described rules and strategy for the game and was bound together with a similar text on whist.

In English, the word "backgammon" is most likely derived from "back" and Middle English "gamen", meaning "game" or "play". The earliest use documented by the Oxford English Dictionary was in 1650.

The most recent major development in backgammon was the addition of the doubling cube. It was first introduced in the 1920s in New York City among members of gaming clubs in the Lower East Side. The cube required players not only to select the best move in a given position, but also to estimate the probability of winning from that position, transforming backgammon into the expected value-driven game played in the 20th and 21st centuries.

Rules

The objective is to move all of one's own checkers past those of one's opponent and then remove them from the board. The checkers are scattered at first and may be blocked or hit by the opponent. As the playing time for each individual game is short, it is often played in matches, where victory is awarded to the first player to reach a certain number of points.

Setup

Each side of the board has a track of 12 long triangles, called points. The points are considered to be connected across one edge of the board, forming a continuous track in the shape of a horseshoe, and are numbered from 1 to 24. Each player begins with two checkers on his 24-point, three checkers on his 8-point, and five checkers each on his 13-point and his 6-point. The two players move their checkers in opposing directions, each from his own 24-point towards his 1-point.

Points 1 through 6 are called the home board or inner board, and points 7 through 12 are called the outer board. The 7-point is referred to as the bar point, and the 13-point as the mid point.

Social and competitive play

Club and tournament play

Enthusiasts have formed clubs for social play of backgammon. Local clubs may hold informal gatherings, with members meeting at cafés and bars in the evening to play and converse. A few clubs offer additional services, maintaining their own facilities or offering computer analysis of troublesome plays. Some club leaders have noticed a recent growth of interest in backgammon, and attribute it to the game's popularity on the internet.

A backgammon chouette permits three or more players to participate in a single game, often for money. One player competes against a team of all the other participants, and positions rotate after each game. Chouette play often permits the use of multiple doubling cubes.

Backgammon clubs may also organize tournaments. Large club tournaments sometimes draw competitors from other regions, with final matches viewed by hundreds of spectators. The top players at regional tournaments often compete in major national and international championships. Winners at major tournaments may receive prizes of tens of thousands of dollars.

International competition

Prior to 1979, there was no single world championship competition in backgammon, although a number of major tournaments were held in Las Vegas, Nevada and the Bahamas. Since 1979, the World Backgammon Championship in Monte Carlo has been widely acknowledged as the top international tournament. The Monte Carlo tournament draws thousands of players and spectators, and is played over the course of a week.

By the 21st century, the largest international tournaments had established the basis of a tour for top professional players. Major tournaments are held yearly in St. Tropez, Rio de Janeiro, Dallas, and Venice. PartyGaming sponsored a tournament in the Bahamas in January 2007 with a prize pool of one million dollars, the largest for any tournament to date.

Gambling

When backgammon is played for money, the most common arrangement is to assign a monetary value to each point, and to play to a certain score, or until either player chooses to stop. The stakes are raised by gammons, backgammons, and use of the doubling cube. Backgammon is sometimes available in casinos. As with most gambling games, successful play requires a combination of luck and skill, as a single dice roll can sometimes significantly change the outcome of the game.

Software

Play and analysis

Backgammon has been studied considerably by computer scientists. Neural networks and other approaches have offered significant advances to software for gameplay and analysis.

The first strong computer opponent was BKG 9.8. It was written by Hans Berliner in the late 1970s on a DEC PDP-10 as an experiment in evaluating board game positions. Early versions of BKG played badly even against poor players, but Berliner noticed that its critical mistakes were always at transitional phases in the game. He applied principles of fuzzy logic to improve its play between phases, and by July 1979, BKG 9.8 was strong enough to play against the ruling world champion Luigi Villa. It won the match, 7–1, becoming the first computer program to defeat a world champion in any board game. Berliner stated that the victory was largely a matter of luck, as the computer received more favorable dice rolls.

In the late 1980s, backgammon programmers found more success with an approach based on artificial neural networks. TD-Gammon, developed by Gerald Tesauro of IBM, was the first of these programs to play near the expert level. Its neural network was trained using temporal difference learning applied to data generated from self-play. According to assessments by Bill Robertie and Kit Woolsey, TD-Gammon's play was at or above the level of the top human players in the world. Woolsey said of the program that "There is no question in my mind that its positional judgment is far better than mine."

Neural network research has resulted in two modern commercial programs, Jellyfish and Snowie as well as the shareware BGBlitz and the free software GNU Backgammon. These programs not only play the game, but offer tools for analyzing games and offering detailed comparisons of individual moves. The strength of these programs lies in their neural networks' weights tables, which are the result of months of training. Without them, these programs play no better than a human novice. For the bearoff phase, backgammon software usually relies on a database containing precomputed equities for all possible bearoff positions.

Internet play

Backgammon software has been developed not only to play and analyze games, but also to facilitate play between humans over the internet. Dice rolls are provided by random or pseudorandom number generators. Real-time online play began with the First Internet Backgammon Server in 1992. It is the longest running non-commercial backgammon server and retains an international community of backgammon players. Yahoo Games offers a Java-based online backgammon room, and MSN Games offers a game based on ActiveX. Online gambling providers began to expand their offerings to include backgammon in 2006. (Credit: Wikipedia).