Go opening theory

In the game of Go, the term opening theory refers to concepts which underlie where, why, in what order, and in what shapes the first several moves are played. [The opening is normally around 20 ply long.] The middle game typically begins once the basic foundational areas called "frameworks" [ Framework in English translates "moyo" in Japanese.] are established and "fighting" begins. [This occurs when moves directly attack an opponent's weak groups, with the serious possibility of killing it.]

The opening is conceptually and traditionally divided for study into the sequences that are "whole board" openings [ The Japanese term "fuseki" is also current in English.] and those that are "corner" openings ["Joseki" in Japanese, meaning 'set pattern', is current in English usage.] . Each type constitutes a series of plays which have been studied for their balance (with the other) as well as for countermoves.

For a standard board [I.e. a 19x19 line goban; essentially no theory for smaller boards gets into print.] , the most basic single concept for the opening is that "plays in the corners are more efficient for making territory than plays on the sides or in the center."

Concepts

Opening theory is less dominant in terms of study, for those wanting to reach a good amateur level, than in chess or "shogi". It is, however, an important component of Go knowledge, though there is no single, codified source for it. [There are 'joseki dictionaries' and 'fuseki dictionaries'. The largest joseki dictionaries contain around 50000 variations; the usual estimate is that a professional player would know about 10% of that number of corner opening lines. Fuseki dictionaries have never been produced in any comparable degree of comprehensiveness; the Large Fuseki Dictionary (布石大事典) of the Nihon Ki-in has around 1000 representative openings.]

The standard sequences for the joseki in many cases come to a definite end, after which both players should move elsewhere. In some cases a sharp local struggle breaks out, which neither player should neglect. For those cases, the result of the opening may develop out of a 10×10 corner area into the rest of the board. Analysis without taking into account what other stones are in place then becomes somewhat meaningless. The longest 'book' corner openings are about 50-ply. [There are some localised variations of this length in the "kado" variation of the "nikkentakabasami", and in the "taisha", where in fact a ko fight may arise.]

Most corner openings do not have special or picturesque names. A few that do are known by Japanese names: the "taisha", the "nadare" (avalanche), the [http://senseis.xmp.net/?MagicSword Magic sword of Muramasa] . These are amongst the most complex, and are contraindicated for novices.

Whole-board openings

Because each early move is typically isolated, and neither forced nor forcing, [I.e. not a "sente" play; this is not always true, but covers most styles until a "joseki" starts.] patterns for play on the whole board have seen much less systematic study than for "joseki", which in contrast often involve contact plays which require specific and immediate responses. Hence a game of Go may easily explore an unfamiliar path.

Only a relatively small proportion of openings have a recognised name. These include the Three stars opening ("sanrensei"), Two stars opening ("nirensei"), "Pinwheel" or Shusaku opening and Chinese opening (Chinese fuseki). To be more precise, these are names for the moyo formations which Black makes on one side of the board. Since White has a choice of perhaps two dozen legitimate variations on the other side, these are in fact large complexes of openings.

The Chinese opening, which has an intricate history but was indeed developed by Chinese players, was very popular from about 1970 onwards, and has by go standards a thoroughly-researched theory.

Joseki

"Joseki" are "sequences" of moves which have been
* played and documented in high-level play, and
* studied and deemed as consisting of optimal (balanced) moves for both sides.

"Joseki" is a Japanese word (定石) (Korean "jungsuk"), where "jo" (定) means "fixed" or "set", and "seki" (石) means stone(s). It thus literally means "set stones", as in "set pattern". Variations are shown to lead to different positional advantages and disadvantages for the two players in certain overall game situations. If Black and White both play the "joseki" correctly, they should achieve a balanced result within that particular corner; neither should have a large advantage, unless the opponent makes a mistake. [On the other hand, the evaluation of the result as fair has to take into account both "who started in the corner", and "who ended the sequence". The first player in a corner expects some advantage; the last player loses the initiative.] "Balance" typically refers to an equitable trade-off between securing "territory" in the corner versus making good "thickness" toward the sides and center. In choosing "joseki", the stronger player will generally seek to create complications, while the weaker player tries to keep things simple.

In application these concepts are in fact very dynamic, and often "joseki" are deviated from depending on the needs of the situation, and the opportunities available. While learning "joseki" is a tool to defend against a local loss, players can seek to take advantage by deviating from the "joseki".

Usually josekis happen in corners in the opening stage. However, on a higher level, there are also josekis for the middle game, many of which are follow-ups to earlier joseki. Learning these middle game joseki is one of many steps to becoming truly strong.

The current body of "joseki" are not fixed, but patterns that have gained acceptance in professional games. That is, they form a consensus judgement that might change in the future, or with certain caveats. Hence the basic definition may be misleading for new players in that joseki can be misconstrued as foolproof and unalterable, and are otherwise optimal for all situations. Many joseki are in fact useful only for study within an artificially confined corner, and in real play are only considered good form when used in proper combination with other plays on the board (ie. other joseki and fuseki moves). Knowing a particular "joseki" simply means that one knows a sequence of moves, resulting in a balance or fair trade-off between their positions. This is in practice much easier than appraising how "joseki" relate to the rest of the board —hence "knowledge of joseki" is regarded as shallow, when compared with the ability to integrate a strategy into a complex game landscape.

There is a go proverb that states that "learning "joseki" loses two stones in strength," meaning that rote learning of sequences is not advantageous. Rather learning "from" "joseki" should be a player's goal. Hence the study of joseki is regarded as a double-edged sword and useful only if learned "not by rote" but rather by understanding the principles behind each move.

Every "joseki" should be used as a specific tool that leaves the board in a particular shape. Just as using an improper tool in machinery can be devastating, choosing the wrong "joseki" can easily be worse than improvising one's own moves.

In his book "A Way of Play for the 21st Century", Go Seigen compared choosing the proper joseki to choosing the proper medicine —"pick the right one, and you feel better. Pick the wrong one and you die."(par.)
Rui Naiwei similarly remarked that "playing joseki is easy [but] choosing the right one [in a game] is hard."(par.)

A "joseki" may fall out of use for various reasons, some of which may often seem minor to the amateur player, and professionals may consider one variation suboptimal for a very specific reason.

There is no definitive guide to what is "joseki"; the situation with "joseki" dictionaries is similar to that of natural language dictionaries, in that some entries are obsolete and the listing is not likely to be complete. Studying "joseki" is only important part of developing one's strength as a player at some levels; the study of life and death and middle-game fighting are considered to be more important.

History

Go openings have been studied in depth for many centuries, and center upon concepts of finding balance with the opponent. Because black moves first, opening moves for black are based on the concept of exploiting that first-move advantage (along with sente) to gain influence (or strength) and thus establish areas of territory.There is no complete theory of go, simply because the number of possible variations makes any literal study impossible. Hence even the opening is subject to changes of fashion, and also some notable periods of innovation.

Certain professional players are known for their use of specific or innovative types of openings, and their ability to combine their use of those openings with other strengths in competitive play.

The 10-10 point

Go Seigen played his third move (Black 5) on tengen, in a 1933 game against Honinbo Shusai, the top player of the time. Go lost the controversial 4-month game, which was played over 14 sessions in a "ryokan" in Tokyo from 16 October 1933 to 19 January 1934.

Notes

External links

* [http://waterfire.us/joseki.htm Kogo's Joseki Dictionary]
**Extensive repository of the most common joseki, stored in the smart go format.
* [http://senseis.xmp.net/?AboutTheOpening Opening article at Sensei's library]
**This is the introductory opening article at the Go wiki "Sensei's Library".
It branches out into several sub-articles and covers most of the basic opening patterns.
* [http://senseis.xmp.net/?DictionariesPage Sensei's Library, information about go dictionaries]
* [http://www.msoworld.com/mindzine/news/orient/go/learn/golearn.html Go Learn - openings]
**Series of articles on openings written by Charles Matthews 3-"dan".