Go

Go, Weiqi, Wei'chi, Baduk

Go, also known as Weiqi or Wei'qi, Wei'chi in Mandarin Chinese (围棋, traditional chinese : 圍棋), and Baduk or Padhook in Korean, is a strategic, deterministic two-player board game originating in ancient China, before 200 BC. The game is now popular throughout East Asia and on the Internet (see this list of Go servers). The object of the game is to place stones so they control a larger board territory than one's opponent, while preventing them from being surrounded and captured by the opponent.

The English name Go originated from the Japanese pronunciation 'go' of the Chinese characters. In Japanese the name is written 碁. The Chinese name Wéiqí roughly translates as 'encirclement chess', the 'board game of surrounding', or the 'enclosing game'. The game is also known as Igo in Japanese. In Russian the name is written Го.

Overview of the game

The game of Go is played by alternately placing stones on a grid. The two players, black and white, engage to maximize the territory they control, seeking to surround large areas of the board with their stones, to entrap any opposing stones that invade these areas, and to protect their own stones from capture.

The strategy involved can become very subtle and complex. Some high-level players spend years perfecting strategy. Go is considered by some to be the ultimate strategy game, superior in depth of complexity to Chess, Xiangqi, and Shogi.

Go is typically classified as an abstract board game. However, a resemblance between the game of Go and war is often suggested. The Chinese classic The Art of War, for instance, has sometimes been applied to Go strategy as well. On the other hand, general strategies of Go are well described by proverbs and are applied in other contexts such as management.

Real wars end when the participants sign treaties. Likewise, in Go, the players have to agree that the game has ended. Only then are the score and the winner finally determined.

History

In many East Asian cultures, Go was considered one of the most important skills a civilized person could learn.

The origins of the game lie in China and the earliest references come from China in the 6th century BC (548 BC, from Zuo Zhuan). Except for changes in the board size and starting position, Go has essentially kept the same rules since that time, which quite likely makes it the oldest board game still played today.

According to legend, the game was used as a teaching tool after the ancient Chinese emperor Yao ? (2337 - 2258 BC) designed it for his son, Danzhu, who he thought needed to learn discipline, concentration, and balance. Another suggested genesis for the game states that in ancient times, Chinese warlords and generals would use pieces of stone to map out attacking positions. Further and more plausible theories relate Go equipment to divination or flood control.

Before the industrial age in China, Go was long perceived as the popular game of the elite aristocratic class while Xiangqi (Chinese chess) was perceived as the game of the masses. Go was considered one of the cultivated arts of the Chinese scholar gentleman (junzi), along with Calligraphy, Painting and playing the Guqin.

Go had reached Japan from China by the 7th century, and gained popularity at the imperial court in the 8th. By the beginning of the 13th century, the game was played in the general public in Japan.

Early in the 17th century, the then best player in Japan, Honinbo Sansa, was made head of a newly founded Go academy (the Honinbo school, the first of several competing schools founded about the same time), which developed the level of playing greatly, and introduced the martial arts style system of ranking players. The government discontinued its support for the Go academies in 1868 as a result of the fall of the Tokugawa shogunate.

In honour of the Honinbo school, whose players consistently dominated the other schools during their history, one of the most prestigious Japanese Go championships is called the 'Honinbo' tournament.

Historically, Go has been unequal in terms of gender. However, the opening of new, open tournaments and the rise of strong female players, most notably Rui Naiwei, has in recent years legitimised the strength and competitiveness of emerging female players.

Around 2000, in Japan, the manga (Japanese comic) and anime series Hikaru no Go popularized Go among the youth and started a Go boom in Japan. In January 2004, the Hikaru no Go manga began running in the US (monthly) edition of Shonen Jump. Whether this will lead to a strong following in the US is yet to be seen.

Scott A. Boorman's The Protracted Game: A Wei-Chi Interpretation of Maoist Revolutionary Strategy likens the game to historical events, saying that the Maoists were better at surrounding territory.

Nature of the game

Although rules of Go can be written so that they are very simple, the game strategy is extremely complex. Go is a perfect information, deterministic, strategy game, putting it in the same class as chess, checkers (draughts), and reversi (othello). It greatly exceeds draughts and reversi in depth and complexity, and transcends even the complexity of chess. Its large board and lack of restrictions allows great scope in strategy. Decisions in one part of the board may be influenced by an apparently unrelated situation in a distant part of the board. Plays made early in the game can shape the nature of conflict a hundred moves later.

The game emphasizes the importance of balance on multiple levels, and has internal tensions. To secure an area of the board, it is good to play moves close together; but to cover the largest area one needs to spread out. To ensure one does not fall behind, expansionist play is required; but playing too broadly leaves weaknesses undefended that can be exploited. Playing too low (close to the edge) secures insufficient territory and influence; yet playing too high (far from the edge) allows the opponent to invade. Many people find the game attractive for its reflection of the contradictary demands found in real life. Indeed, a common saying is 'life is like Go'.

The game complexity of Go is such that even an introduction to strategy can fill a book, and many good introductory books are available. See Go strategy and tactics for a very brief introduction to the main concepts of Go strategy.

It is commonly said that no game has ever been played twice. This may be true: On a 19 x 19 board, there are about 3^361 * 0.012 = 2.1 * 10^170 possible positions, most of which are the end result of about (120!)^2 = 4.5 * 10^397 different (no-capture) games, for a total of about 9.3 * 10^567 games. Allowing captures gives as many as 10^{7.49 * 10^48} possible games, all of which last for over 4.1 * 10^48 moves! (For two comparisons: the number of legal positions in chess is estimated to be between 10^43 and 10^50; and physicists estimate that there are not more than 10^90 protons in the entire visible universe.)

Go equipment

Although one could play Go with a piece of cardboard for a board and a bag of plastic tokens, many Go players pride themselves on their game sets.

The traditional Go board (called a goban in Japanese) is solid wood, from 10-18 cm thick, and often stands on its own attached legs. It is preferably made from the rare golden-tinged Kaya tree (Torreya nucifera), with the very best made from Kaya trees up to 700 years old. More recently, the California Torreya (Torreya californica) has been prized for its light color and pale rings. Other woods often used to make quality table boards include Hiba (Thujopsis dolabrata), Katsura (Cercidiphyllum japonicum), and Kauri (Agathis). It is important to note that 'Shin Kaya,' so called, is a merchant's term which, while it may not deceive Asian buyers, does confuse Americans; the term shin means 'new' (as in shinbun, 'newspaper'), so 'shin kaya' is best translated 'faux kaya' - and indeed the woods so employed are biologically unrelated.

Traditional stones are made so that black stones are slightly larger in diameter than white; this is probably to compensate for the optical illusion created by contrasting colours that would make equal-sized white stones appear larger on the board than black stones. The difference is slight, and since its effect is to make the stones appear the same size on the board, it can be surprising to discover they are not.

Rules

Two players, black and white, take turns placing a stone on the points (intersections) of a 19 by 19 board (grid). Black moves first. Other board sizes do exist, such as 13 by 13 and 9 by 9 but 19 by 19 is the preferred board in tournaments.

Stones must have liberties (empty adjacent points) to remain on the board. Stones connected by lines are called chains, and share their liberties.

When a stone or a chain of stones is surrounded by opponent stones, so that it has no more liberties, it is captured and removed from the board.

If a stone has no liberties as soon as it is played, but simultaneously removes the last liberty from one or more of the opponent's chains, the opponent's chains are captured and the played stone is not.

'Ko rule': A stone cannot be played on a particular point if doing so would recreate the board position that existed after the same player's previous turn.

A player may pass instead of placing a stone. When both players pass consecutively, the game ends and is then scored.

A player's score is the number of empty points enclosed only by his stones plus the number of points occupied by his stones. The player with the higher score wins. (Note that there are other rulesets that count the score differently, yet almost always produce the same result.)

This is the essence of the game of Go. The risk of capture means that stones must work together to control territory, which makes the gameplay very complex and interesting.

Strategy

Basic strategic aspects include the following:

* Connection: Keeping one's own stones connected means that fewer groups need defense.
* Cut: Keeping opposing stones disconnected means that the opponent needs to defend more groups.
* Life: This is the ability of stones to permanently avoid capture. The simplest way is for the group to surround two 'eyes' (separate empty areas), so that filling one eye will not kill the group and is therefore suicidal.
* Death: The absence of life, resulting in the removal of a group.
* Invasion: Penetration into an opponents claimed territory as a means of swaying the balance of territory.

Philosophy

Go is deep, as playing against any stronger player will demonstrate (depth of the game as established by ELO ranking in Go). With each new level (rank) comes a deeper appreciation for the subtlety involved, and for the insight of stronger players. Beginners often start by randomly placing stones on the board, as if it were a game of chance - and they inevitably lose to experienced players. But soon an understanding of how stones connect to form strength develops, and shortly afterward a few basic common opening sequences may be understood. Learning the ways of life and death helps to develop one's situational judgement.

Further experience yields an understanding of the board, the importance of the edges, then the efficiency of developing (in the corners first, then sides, then centre). Soon, the advanced beginner understands that territory and influence are somewhat interchangeable - but there needs to be a balance. Best is to develop more or less at the same pace as the opponent, in both territory and influence. This intricate struggle of power and control makes the game highly dynamic.

Computers and Go

Although much effort has gone in to programming computers to play Go, even the strongest programs are no better than an average club player, and would easily be beaten by a strong player even getting a nine-stone handicap. Strong players have even beaten computer programs at handicaps of twenty-five stones. Of course, strong players do not currently have much interest in computer Go programs as opponents, as they do not yet play well enough. This is attributed to many qualities of the game, including the 'optimising' nature of the victory condition, the large number of legal moves, the large board size, the nonlocal nature of the Ko rule, and the high degree of pattern recognition involved. On the other hand, a chess-playing computer, Deep Blue, beat the world champion in 1997. For this reason, many in the field of artificial intelligence consider Go to be a better measure of a computer's capacity for thought than chess.

On the other hand, none of these factors prevents computers from playing far better than human players in certain endgame situations, exactly as in the case of chess. In chess, this is due to the use of end game tablebases; in Go, to an application of the kind of game analysis pioneered by John H. Conway, who invented surreal numbers to analyze games and Go endgames in particular, an idea much further developed in application to Go by Elwyn R. Berlekamp and David Wolfe. It is outlined in their book, Mathematical Go (ISBN 1568810326). While not of general utility in most play, it greatly aids the analysis of certain classes of positions.

Go ranks and ratings

In countries where Go is popular, ranks are employed to indicate playing strength. From about the sixteenth century, the Japanese formalised the teaching and ranking of Go. The system is comparable to that of martial arts schools; and is considered to be derived ultimately from court ranks in China.

Beginning players today start at a rank of between 25 and 30 kyu. The kyu ranking then decreases in magnitude as the player becomes stronger, dropping down to 1 kyu or 1k. Since beginners will commonly progress through elementary concepts quickly, it may be difficult to set a solid kyu ranking for new players. Players who have progressed through the kyu ranks and passed the 1 kyu mark are then ranked at 1 dan or 1d, sometimes called shodan. The player then could advance through the amateur dan ranks up to amateur 7 dan, which only few players achieve. That playing level is roughly equivalent to where the ranks for professionals start with pro 1 dan going up to 9 dan (also sometimes called ping or p as in 9p to avoid confusion between a 1 dan professional and a weaker amateur 6 dan). The distinction between each amateur rank is, by definition, one handicap stone. Professional ranks are awarded by professional organizations and though they are less well defined, they are closer, so that an average 1p might need three handicap stones against a prime 9p (although they would play even games if they were to meet in a tournament).

Timing

Like many other games, a game of Go may be timed. There are four typical methods of timing a game:

* Absolute: a specific amount of time is given for the entire game, regardless of how fast or slow each player is. This is extremely rare.
* Byo-Yomi (Japanese Timing): After the main time is depleted, a player has a certain number of time periods (typically around 30 seconds). After each move, the number of time periods that the player took (possibly zero) is subtracted. For example, if a player has three 30-second time periods and takes 30 or more (but less than 60) seconds to make a move, he loses one time period. With 60-89 seconds, he loses two time periods, and so on. If, however, he takes less than 30 seconds, the timer simply resets without subtracting any periods. This is written as (maintime) + (byo-yomi time period)x(number of byo-yomi time periods).
* Canadian Byo-Yomi: After the main time is depleted a player must make a certain number of moves within a certain period of time. For example, 5 moves within 2 minutes. If 5 moves are made in time, the timer resets to 2 minutes again. This is written as (main time)/(byo-yomi time period)/(number of moves to be completed in each byo-yomi time period). (The Origins of Canadian Byo-Yomi)
* Progressive Byo-Yomi: usually this is based on Canadian Byo-Yomi, where after main time is depleted the first number of moves must be played in a time, but the next number of moves may be different and played in a different amount of time. For instance, in one amateur tournament the main time of 50 minutes was followed by twenty moves in five minutes, then forty moves in five minutes, then sixty moves in five minutes (the last time period being repeated until the game ended). Thus, this tournament's timing was written 50+20/5+40/5+60/5 (it is common to leave minutes as numbers without units while seconds are usually written in the form 5s).

Japanese Timing is equivalent to Canadian Byo-Yomi when the 'certain number of moves' is equal to one.

Top players

Although the game was invented and developed in China, Japanese players dominated the international Go scene for most of the twentieth century. However, top players from China (since the 1980s) and South Korea (since the 1990s) have reached an even higher level. Nowadays, top players from these three countries are of comparable strength, although top Korean players seem to have an edge, dominating the major international titles, winning 23 tournaments in a row between 2000 and 2002. All three countries have a number of professional Go tournaments. The top Japanese tournaments have a prize purse comparable to that of professional golf tournaments in the United States though tournaments in China and Korea are less lavishly funded.

Players from other countries have traditionally been much weaker, except for some players who have taken up professional courses in one of the Asian countries. This is attributed to the fact that details of the game have been unknown outside of Asia for most of the game's history. A German scientist, Otto Korschelt, is credited with the first systematic description of the game in a Western language in 1880; it was not until the 1950s that Western players would take up the game as more than a passing interest. In 1978, Manfred Wimmer became the first Westerner to receive a professional player's certificate from an Asian professional Go association. It was not until 2000 that a Westerner, Michael Redmond, achieved the top rank awarded by an Asian Go association.

Go terms

Go terms and concepts are important. Technical terms are likely to be met in books and articles about go in English, and in other languages also. As one advances in skill, one becomes more aware of the subtlety behind stronger play that transcends calculable mechanical thinking. Conceptual thinking is what allows intelligent beings to deal with very complex issues with some basic rules of understanding. This exists in go to a degree greater than in other games, as placed stones exert a hard-to-quantify influence of play over the board, and these effects need to be understood for a player to rise to the dan ranks.

Although Go originated in China, the current English and Western technical vocabulary borrows a high proportion of terms from the Japanese language, since it was through Japan that Go was introduced to Western culture. Many of them are from a jargon, used for technical go writing and to some extent specially developed for go journalism; in some cases the technical meaning of a word may differ from a dictionary meaning coming from ordinary usage.

Board positions
NB The go convention is that the corner points of the board are called (1, 1) points; and lines are counted in from the edge.

* Hoshi or star point : an intersection traditionally marked with a small dot on the board. These are either
o a (4, 4) point in an empty corner,
o a (4, 10) point on one of the sides, or
o Tengen: the (0, 0) point at the centre of the 19×19 goban.
* Komoku: a (4, 3) or (3, 4) point in a corner; meaning 'little point' in Japanese.
* Mokuhazushi: a (3, 5) or (5, 3) point in a corner; roughly 'separated point' in Japanese.
* Sansan: a (3, 3) point in a corner; literally '3, 3' in Japanese.

Atari
'Atari' (Chinese: 'dachi'; Korean 'dansoo') is a term used for a positional state where a stone or group of a number of stones has only one liberty, and may be captured on the next move if it is not given attention. It can be a verb to describe the act of placing a group under atari, as well as an adjective to describe the status of a group, as being 'in (the state of) atari'. It may be spoken aloud during the game by the instigator, as a courtesy to call the opponent's attention to the fact that his stone or group is endangered; but that is now considered obsolete etiquette of the game and is not currently used.

Seki
Seki is a Japanese term used to describe a situation that cannot be resolved into simple life-and-death. For example, a capturing race may end in a position in which neither player finds it advantageous to continue to try to capture the other. There are numerous types of seki position that can arise, characterised as cases in which neither player adds a play to groups that do not have two eyes. The area remains untouched; at the end all groups involved are deemed alive, but no territory is scored. (This is under the Japanese rules.)

Sente and gote
Sente is the gain of initiative; the opposite of this is gote (loss of initiative). The initiative being a move that carries initiative, by requiring a follow-up. For example, 'white,' after making a move that is sente, and it is responded to (in gote) has the choice of where to play next. White is therefore said to 'have sente.'

Miai
A pair of points on the board that are equivalent in terms of value with respect to a group's development or survival. Miai can be seen in the fuseki stage on a large scale or in a simple life and death problem, such as a straight four-space eye. This shape is alive, because if white plays b, black can answer with a and vice versa. This can be seen in the Avalanche joseki.

Aji
The closest English one could use is 'latent potential.' From the Japanese, aji is the word for taste, and in go refers to the lingering quality that even dead stones will provide possible avenues of subtle play. Though aji may not be used at all, it has a bearing on the course of the game. Good aji is when your groups are strong, and have little or no possibility of being compromised. Bad aji, is where dead stones carry a latent threat of compromising an existing area, should the situation become ripe.

Liberty
A free space that is immediately adjacent to a stone either directly up, down, left or right from it or be connected through a continuous string of same-colored stones to such a free space. A single stone must always have at least one liberty to survive and a group should usually have at least two guaranteed liberties (eyes) to be considered alive. If a group is surrounded, having at least two eyes ensures that it cannot be captured by an opponent in most cases.

Moyo
A framework for potential territory which usually consists of unconnected stones with some distance between them. The early game usually consists of competing for moyo by attempting to invade or reduce your opponent's.

Korigatachi
It's translated as 'over-concentrated'. If a player uses his stones in an inefficient way, the result will be korigatachi. So, knowing something about korigitachi should tell you how to avoid it.

Sabaki
Light and flexible shape development.

Thickness
Also called influence. Thickness refers to a kind of influence, where an area is developed beyond the level of the area around it. A large wall, for example, is a common example of thickness, and if that wall has no compromising weaknesses in it, will provide a help to its other stones in the area. Considering the proverb-- 'do not try to make territory from thickness', stronger players will avoid making strong areas any stronger (as this will waste moves). Instead they will play in underdeveloped areas and allow their thickness elsewhere to have a subtle influence over play on the rest of the board.

Kikashi
Kikashi is a forcing move in the context of an attack. Unlike sente, though, a move is kikashi when it yields a high efficiency in play by causing the opponent to regard that move in making a change in its course of action. A kikashi stone can generally be sacrificed but meanwhile it still might have an advantage, e.g. a ladder breaker, while the answering move has no value at all. Moves can be kikashi, or not, depending on whether they are answered with appropriate sophistication or not. If the answering move strengthens the position, then the play is not kikashi but aji keshi (ruining one's own potential).

Yosu-miru
A probe. A yosu-miru move is, in some sense, a sacrifice of a stone, but is designed to yield a very sophisticated kind of information about a developing group and how best to attack it, based on its response. Yosu-miru draws on other concepts of kikashi and aji, and korigatachi in order to understand it fully.

As such, yosu means situation or the state of things, and miru is 'to see', thus 'yosu o miru', to 'see how things stand'. In Japanese this expression is usually used to say that it's better to wait and see before taking an action (e.g. 'shibaraku yosu o miru beki da', it's better to wait and see for a little while). It is not a single word or a set phrase except in Western Go literature, and 'probe' is the preferred word, being self-explanatory and actually used by the speakers of its originating language.

A list of commonly used Go Terms

* Aji -- Aji means possibilities which are left in a position.
* Atari -- The state of a stone or group of stones that has only one liberty left.
* Capturing race -- See Semeai.
* Chain -- A chain is a group of stones that are all connected along the lines of the board.
* Connection -- Two or more stones are connected if they belong to the same chain, i.e. when they can only be taken from the board together.
* Cut -- A cut is the action or the move which separates two almost connected groups of stones.
* Dame -- An empty point adjacent to a stone; a Basic liberty: neutral points.
* Damezumari -- A shortage of liberties.
* Death -- A group is dead when its owner cannot, playing first with correct play, make it live with two eyes or in seki or make a ko for life.
* Dragon -- A dragon is a long connected shape spanning large areas of the board.
* Endgame -- The endgame is the final stage of the game when the status of all big groups is already determined and the remaining moves aim at expansion of own territory and reduction of the territory of the opponent.
* Eye -- An empty space surrounded by stones of one colour.
* Fuseki -- Fuseki is a Japanese go term meaning arraying stones for battle, referring to opening play in go.
* Geta -- See Net.
* Goban -- Go board.
* Gote -- A move or position in which the opponent does not need to answer.
* Group -- One or more isolated stones or chains (strings) of stones of one colour, hanging together as if effectively connected.
* Hane -- A hane is a move which 'reaches around' one or more of the opponent's stones.
* Handicap -- Giving stones to a weaker player to level the playing field.
* Honte -- A move which is honte ('the proper move') is one that is played to reduce the amount of aji in one's position.
* Influence -- Influence is a long-range effect that stones have on each other.
* Joban -- A Japanese go term for the beginning phase of the game.
* Joseki -- Joseki are generally agreed-upon sequences of play.
* Kikashi -- Kikashi, a Japanese go term adopted into English (forcing move), is a sente move that produces a certain effect and can then be abandoned without any great loss.
* Killing -- Capturing the opponents stone or group of stones.
* Ko -- A rule to avoid infinitely repeating positions.
* Ko Threat -- A ko threat is a move with a 'big' follow-up, which you play after your opponent has captured a ko, expecting him to answer it and thus allow you to recapture the ko.
* Komi -- Compensation given to white for black playing first.
* Ladder -- A ladder is a technique for capturing stones where at each step the attacker reduces the defender's liberties from two to one.
* Liberty -- An empty point adjacent to a single stone or chain of stones.
* Life -- State where a group has two eyes, lives in seki or is secure enough to survive an invasion.
* Miai -- Miai denotes that a player has two different options at his or her disposal, such that, if the opponent takes away one, the player can take the other.
* Moyo -- A framework is an area where one player has a large influence, and which potentially could become that player's territory.
* Net -- A net is a technique where one or a few stones are captured by blocking the exits.
* Peep -- A peep in go is a threat to cut (nozoki in Japanese).
* Point -- A point is the intersection of two lines on the go board.
* Ponnuki -- A ponnuki is the process of capturing a single stone, leaving a diamond shape.
* Sansan -- 3-3 point.
* Seki -- Seki, a Japanese go term adopted into English, means mutual life.
* Semeai -- Capturing Race.
* Semedori -- Semedori is a situation in which dead stones must eventually be captured.
* Sente -- Meaning playing first; players have sente if it is their turn and they do not have to answer their opponent's last move (at a particular place).
* Shape -- Form; a quality of a group of stones of the same color.
* Shicho -- Ladder.
* Tedomari -- Tedomari means the last play.
* Tengen -- The center point of the go board.
* Tenuki -- Tenuki, a Japanese go term adopted into English, denotes playing somewhere else.
* Territory -- A part of the board that is surrounded by stones belonging to a living group, and in which the opponent cannot make a living group.
* Tesuji -- A tesuji is a clever play, the best play in a local position, a skillful move, a special tactic.
* Tsumego -- life and death problem.
* Vital Point -- Key point (for either player), in either the local, or, perhaps less commonly, the global context.
* Yose -- Yose, a Japanese go term adopted into English, are moves that approach fairly stable territory, typically enlarging one's own territory while reducing the opponent's.
* Zokusuji -- Zokusuji literally means 'crude line of play' and is often translated as 'vulgar move'.

From Wikipedia and Sensei's library.