Go is a two-player board game that originated in China. Players take turns placing black and white stones on the intersections of a board, seeking a higher score by surrounding territory, connecting their own stones, and capturing their opponent’s stones. Go has relatively few rules, but the interplay between local fighting and the overall board position creates a complex strategic system. It is both a recreational activity and a competitive pursuit with a professional system and international tournaments. (en.wikipedia.org)
Origins and Spread
The exact date of Go’s invention and the identity of its inventor are unknown. The account that the legendary ruler Yao created Go to teach his son Danzhu is a legend and should not be treated as historical fact. Chinese texts from the pre-Qin period already contain references to the game: the Analects mentions “bo and yi,” while the Mencius describes Yi Qiu teaching people to play, indicating that Go already had an established place in society at that time. (britgo.org)
Go later spread to the Korean Peninsula and Japan. Japan had encountered the game before the eighth century and subsequently developed traditions of play at court, in temples, and among the general public. In 1612, the Japanese shogunate began providing stipends to players. This gradually led to the establishment of the four Go houses—Honinbo, Inoue, Yasui, and Hayashi—which fostered the training of professional players and the study of the game. Go began spreading in Europe in the late nineteenth century; in the twentieth century, promotional efforts by Asian Go communities helped make it an international game. (britgo.org)
Equipment and Basic Rules
A standard board has nineteen horizontal and nineteen vertical lines, creating 361 intersections. Nine-by-nine and thirteen-by-thirteen boards are also used for teaching and shorter games. Stones are placed on intersections rather than inside squares, and Black generally plays first. Once placed, stones do not move unless they are captured and removed. A player may also choose not to place a stone on a turn, which is called passing. (en.wikipedia.org)
Empty intersections immediately adjacent to a stone or a connected group of stones horizontally or vertically are called liberties; diagonal adjacency does not count as a connection. When an opponent occupies a group’s last liberty, the entire group is removed from the board, a process called capture. Most commonly used rules prohibit suicide moves that leave one’s own group without liberties. However, a move is legal if it first captures opposing stones and thereby gains liberties. (britgo.org)
The ko rule restricts cycles of repeated capture. The most basic rule prohibits an immediate recapture in a simple ko that would restore the previous board position; the player must first make a move elsewhere. Some rules use broader superko provisions that prohibit the recurrence of specified earlier positions. Different rulesets do not handle complex cycles in exactly the same way. (britgo.org)
Ending the Game and Scoring
After both players pass consecutively, they usually proceed to confirm the final position and calculate the score. The handling of disputed positions depends on the ruleset in use. Before scoring, players must determine which groups are alive or dead and who owns each territory. Japanese-style territory scoring primarily counts surrounded empty points and captured stones; Chinese-style area scoring primarily counts living stones on the board and the empty points they surround. The two methods often produce the same winner, but may differ in certain edge cases. (en.wikipedia.org)
Even games usually include komi, a number of points awarded to White to compensate for Black’s first-move advantage. The amount of komi varies by ruleset and tournament rather than being a universal fixed value. Players of different strengths can play a handicap game, in which the weaker player takes Black and places several stones on the board in advance, after which White makes the next move. (en.wikipedia.org)
Stone Shapes and Strategy
Life and death concerns whether groups of stones can avoid capture. An internal empty point or space enclosed by a player’s stones is called an eye. A connected group with two separate true eyes can generally withstand direct attempts to capture it. Incomplete eye shapes may form false eyes, so appearance alone is not a reliable guide. There are also seki, or mutual-life, positions: opposing groups share crucial liberties, and either player may be captured first if they rashly fill those liberties. The groups can therefore coexist without each having two eyes. (britgo.org)
A game is commonly divided into the opening, middlegame, and endgame. The opening establishes the overall arrangement of stones, usually prioritizing the corners before developing the sides and center. The middlegame involves attacks, connections, cuts, and struggles over territory. The endgame primarily settles boundaries and compares the value of the remaining moves. These phases have no strict dividing lines: local positions may be settled while fighting continues elsewhere on the board. (en.wikipedia.org)
A joseki is a studied sequence of local moves that produces a roughly balanced result for both players under particular conditions, most commonly in a corner. Choosing a joseki still depends on the surrounding position; it cannot be applied mechanically without regard to the whole board. Nor is Go strategy about capturing as many stones as possible: players must weigh secure territory, the safety of their groups, and influence over future fighting. (en.wikipedia.org)
Ranks and Organizations
Go ranks are generally divided into kyu and dan grades. Lower kyu numbers indicate greater strength; after reaching first dan, higher dan numbers indicate higher ranks. Amateur and professional dan ranks belong to different systems and cannot be compared directly on the basis of matching numbers. Standards for awarding ranks also differ among organizations. (britgo.org)
Modern Go associations oversee professional player training, organize competitions, and promote the game. The Nihon Ki-in was founded in 1924. The International Go Federation was established on March 18, 1982, building on earlier cooperation that included the first World Amateur Go Championship in 1979. Its main activities are organizing international events and promoting Go. (archive.nihonkiin.or.jp)
Computer Go
Go was long an important subject of Artificial Intelligence research. AlphaGo combined deep Artificial Neural Networks with search methods, learning from records of human games and using self-play for Reinforcement Learning. Its policy network selected candidate moves, while its value network evaluated positions. In March 2016, the program defeated professional player Lee Sedol 4–1 in Seoul, marking a major milestone in the development of computer Go. (deepmind.google)