A rollout is an analysis technique for backgammon positions and moves. A rollout consists of playing the same position many times (with different dice rolls) and recording the results. The balance of wins and losses is used to evaluate the equity of the position. Historically this was done by hand, but it is now undertaken primarily by computer programs.
In order to compare two or more ways to move, rollouts can be performed from the positions after each move. Better choices will yield a more favorable position, and thus will win more times (and lose more rarely) in the end.
Computer programs usually play rollouts where the number of games is a multiple of 36, and ensure that the first dice roll is uniformly distributed. That is, 1/36 of the played games will start with a roll of 1-1, another 36th will start with 1-2, and so on. A common length for a rollout is 36x36 = 1296, in which each possible combination is used for the first two rolls. This improves the accuracy of the technique.
Rollouts depend on the availability of a good evaluator. If the computer makes mistakes in particular scenarios, the rollout results may be invalid. For example, if a computer AI's backgame strategy was weak, rollouts starting in a backgame position will skew the equity against the player who chose that strategy. When comparing moves, a weak backgame AI may favor less aggressive style. [1] It is therefore not uncommon to see slightly different outcomes from rollouts done with different programs. [2]
Nevertheless, rollouts whose results are consistently nonintuitive occur, [3] and their results are usually accepted by most backgammon players. Modern backgammon opening theory is mostly based on rollouts. [4]
Backgammon is a two-player board game played with counters and dice on tables boards. It is the most widespread Western member of the large family of tables games, whose ancestors date back nearly 5,000 years to the regions of Mesopotamia and Persia. The earliest record of backgammon itself dates to 17th-century England, being descended from the 16th-century game of Irish.
Dice are small, throwable objects with marked sides that can rest in multiple positions. They are used for generating random values, commonly as part of tabletop games, including dice games, board games, role-playing games, and games of chance.
A solved game is a game whose outcome can be correctly predicted from any position, assuming that both players play perfectly. This concept is usually applied to abstract strategy games, and especially to games with full information and no element of chance; solving such a game may use combinatorial game theory and/or computer assistance.
Computer chess includes both hardware and software capable of playing chess. Computer chess provides opportunities for players to practice even in the absence of human opponents, and also provides opportunities for analysis, entertainment and training. Computer chess applications that play at the level of a chess grandmaster or higher are available on hardware from supercomputers to smart phones. Standalone chess-playing machines are also available. Stockfish, Leela Chess Zero, GNU Chess, Fruit, and other free open source applications are available for various platforms.
Tables games are a class of board game that includes backgammon and which are played on a tables board, typically with two rows of 12 vertical markings called points. Players roll dice to determine the movement of pieces. Tables games are among the oldest known board games, and many different varieties are played throughout the world. They are called 'tables' games because the boards consist of four quadrants or 'tables'. The vast majority are race games, the tables board representing a linear race track with start and finish points, the aim being to be first to the finish line, but the characteristic features that distinguish tables games from other race games are that they are two-player games using a large number of pieces, usually fifteen per player.
Computer Go is the field of artificial intelligence (AI) dedicated to creating a computer program that plays the traditional board game Go. The field is sharply divided into two eras. Before 2015, the programs of the era were weak. The best efforts of the 1980s and 1990s produced only AIs that could be defeated by beginners, and AIs of the early 2000s were intermediate level at best. Professionals could defeat these programs even given handicaps of 10+ stones in favor of the AI. Many of the algorithms such as alpha-beta minimax that performed well as AIs for checkers and chess fell apart on Go's 19x19 board, as there were too many branching possibilities to consider. Creation of a human professional quality program with the techniques and hardware of the time was out of reach. Some AI researchers speculated that the problem was unsolvable without creation of human-like AI.
Nard is an historical Persian tables game for two players that is sometimes considered ancestral to backgammon. It is still played today, albeit in a different form. As in other tables games, the playing pieces are moved around a board according to rolls of dice. It uses a standard tables board, but has a different opening layout and rules of play from that of backgammon.
Acey-deucey is a table game, a family of board games that includes backgammon. Since World War I, it has been a favorite game of the United States Navy, Marine Corps, and Merchant Marine. Some evidence shows that it was played in the early 1900s aboard U.S. Navy ships. The game is believed to be rooted in the Middle East, Greece, or Turkey, where there were variants in which the game started with pieces of the board.
Gul bara is a tables game, an ancient genre of board games that includes Backgammon, Trictrac and Nard. It is also called Rosespring Backgammon or Crazy Narde. The aim of the game is to move all of one's men around the board and bear them off. The first player who bears off all his or her men wins. The game is popular in Bulgaria, Azerbaijan, Greece, Turkey and North Macedonia.
Plakoto (Πλακωτό) is a tables game for two players that is popular in Greece. The object is for the player to bring all 15 pieces around to his or her own home board and then bear them off. The player who bears off all 15 pieces first wins the game. This game is usually played along with two other variants, Févga and Pórtes. Together these three games are called Távli, and are played in sequence usually one after the other. Game is three, five or seven points. A Middle Eastern version of this game is Mahbusa, and the Bulgarian version of Plakoto is known as Tapa and also as Tsillitón (Τσιλλιτόν), in Cyprus. Parlett places Plakoto in the same group as the popular mediaeval game of English, as well as the French games of Tieste and Impérial, the Italian game of Testa and Spanish Emperador.
The first moves of a backgammon game are the opening moves, collectively referred to as the opening, and studied in the backgammon opening theory. Backgammon opening theory is not developed in as much detail as opening theory in chess, which has been widely studied. This is because following the first move in backgammon, there are 21 dice roll outcomes on each subsequent move and many alternative plays for each outcome. Therefore, the tree of possible positions in backgammon expands much more rapidly than in chess; by the third roll there are about 25,000 different possibilities.
Anti-computer tactics are methods used by humans to try to beat computer opponents at various games, most typically board games such as chess and Arimaa. They are most associated with competitions against computer AIs that are playing to their utmost to win, rather than AIs merely programmed to be an interesting challenge that can be given intentional weaknesses and quirks by the programmer. Such tactics are most associated with the era when AIs searched a game tree with an evaluation function looking for promising moves, often with Alpha–beta pruning or other minimax algorithms used to narrow the search. Against such algorithms, a common tactic is to play conservatively aiming for a long-term advantage. The theory is that this advantage will manifest slowly enough that the computer is unable to notice in its search, and the computer won't play around the threat correctly. This may result in, for example, a subtle advantage that eventually turns into a winning chess endgame with a passed pawn.
Computer Othello refers to computer architecture encompassing computer hardware and computer software capable of playing the game of Othello. It was notably included in Microsoft Windows from 1.0 to XP, where it is simply known as Reversi.
TD-Gammon is a computer backgammon program developed in 1992 by Gerald Tesauro at IBM's Thomas J. Watson Research Center. Its name comes from the fact that it is an artificial neural net trained by a form of temporal-difference learning, specifically TD-Lambda.
Computer Arimaa refers to the playing of the board game Arimaa by computer programs.
In backgammon, there are a number of strategies that are distinct to match play as opposed to money play. These differences are most apparent when a player is within a few points of winning the match.
The following is a glossary of terms used in tables games, essentially games played on a Backgammon-type board. Terms in this glossary should not be game-specific, but applicable to a range of tables games.
Ludus Anglicorum, also called the English Game, is an historical English tables game for two players using a board similar to that used today for Backgammon and other games. It is a "strategic game for serious game-players" and was well known in the Middle Ages. At one time it was considered the most popular tables game in England.
Long Nardy, also just Nardy, is a Russian tables game for two players. It is also played in Armenia as Long Nardi or Nardi. It probably originated in the historical Persian game of Nard. It requires a tables board, 15 men apiece and two dice.
Fevga is a popular Greek tables game for two players. It is usually played as one of three different games in succession – the others being Portes and Plakoto – in social gatherings or coffee shops. When played in this way, it is known as Tavli. Very similar games, with slight variations, are Turkish Moultezim, Russian Narde and Egyptian and Lebanese Tawla 31 or Maghribiyyah.
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