View source for Jōseki

{{Short description|Studied sequences of moves in the game of go and shogi}}
{{other uses}}
{{Italic title|reason=[[:Category:Japanese words and phrases]]}}
{{more footnotes|date=December 2011}}
{{GoBoardGame}}
[[Image:San-San-Joseki.jpg|right|300px|thumb|A ''[[San san (Go)|san san]]'' ''jōseki'': Black gets secure territory in the corner, and White gets outside (center) influence.  The result is deemed equal, thus the sequence is a ''jōseki''.]]
In ''[[Go (board game)|go]]'' and ''[[shōgi]]'', a '''''jōseki''''' or '''''jouseki''''' (''[[kanji]]'' characters {{nihongo2|定石}} for go, {{nihongo2|定跡}} for ''shōgi'') is the studied sequences of moves for which the result is considered ''balanced'' for both black and white sides.
==''Go'' ''jōseki''==
In ''go'', because games typically [[go opening theory|start with plays in the corners]], ''go'' ''jōseki'' are usually about corner play as the players try to gain local advantages there in order to obtain a better overall position. Though less common, there are also ''jōseki'' for the middle game. In [[Japanese language|Japanese]], ''jō'' ({{nihongo2|定}}) means "fixed" or "set" and ''seki'' ({{nihongo2|石}}) means stones, giving the literal meaning "set stones", as in "set pattern". In [[Chinese language|Chinese]], the term for joseki is ''dìngshì'' ({{lang|zh|定式}}).
The concept of "balance", here, often refers to an equitable trade-off between securing territory in the corner versus making good ''[[go concepts#Thickness|thickness]]'' toward the sides and the center. In application, these concepts are very dynamic, and, often, deviations from a ''jōseki'' depend upon the needs of the situation and the available opportunities. While learning ''jōseki'' is a tool to defend against a local loss, players always seek to take advantage of weaknesses in the opponent's [[shape (Go)|shapes]], often deviating from the ''jōseki''.
=== Using ''jōseki'' ===
''Jōseki'' are not fixed but comprise patterns that have gained acceptance in professional games; they constitute a consensus that may change with certain caveats. Hence, the basic definition may be misleading for new players in that a ''jōseki'' can be misconstrued as foolproof and unalterable and as optimal for all situations. Many ''jōseki'' are in fact useful only for study within an artificially confined corner,<ref>{{cite web|title=Even Game Joseki|url=http://senseis.xmp.net/?EvenGameJoseki|publisher=[[Sensei's Library]]|access-date=26 December 2011}}</ref> and in real play are only considered good form when used in proper combination with other plays on the board (i.e. other ''jōseki'' and ''[[fuseki]]'' moves).
Knowing a particular ''jōseki'' simply means that one knows a sequence of moves, resulting in a balance or fair trade-off between black and white positions. This is in practice much easier than appraising how ''jōseki'' relate to the rest of the board&nbsp;– hence, ''knowledge of jōseki'' is regarded as shallow, when compared with the ability to integrate a strategy into a complex game landscape.
One [[go proverb]] states that "learning ''jōseki'' loses two stones in strength," which means that the [[rote learning]] of sequences is not advantageous; rather, learning ''from'' a ''jōseki'' should be a player's goal.<ref>{{cite book|first=Toshiro|last=Kageyama|page=152|publisher=The Ishi Press|title=Lessons in the Fundamentals of Go|translator=James Davies|date=1978|location=Tokyo, Japan|isbn=4906574289}}</ref>  Hence, the study of ''jōseki'' is regarded as a double-edged sword and useful only if learned by understanding the principles behind each move, instead of by rote. Every ''jōseki'' 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 ''jōseki'' 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 ''jōseki'' to choosing the proper medicine: "Pick the right one, and you feel better. Pick the wrong one, and you die." {{bracket|[[paraphrase|par.]]}} [[Rui Naiwei]] <!-- not sure-->similarly remarked that "playing ''joseki'' is easy [but] choosing the right one [in a game] is hard." [par.]
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It is sometimes also used outside of Go in this sense; in everyday speech, "This is the ''joseki'' here" may apply to just about anything.-->
A ''jōseki'' may fall out of use for various reasons, some of which may often seem minor to the amateur player; professionals may consider one variation suboptimal for a very specific reason&nbsp;– one which strong amateurs are not likely to exploit.
There is no definitive guide to what is a ''jōseki''; the situation with ''jōseki'' dictionaries is similar to that of natural language dictionaries: some entries are obsolete, and the list is likely to be incomplete.
=== Basic ''jōseki'' ===
[https://sentego.net/joseki-dictionary/ Corner ''jōseki''] conventionally start with one player occupying a corner point, in an empty 19×19 area of the board, and the other player replying with an ''approach move'' (Japanese: ''kakari''). The initial play in the corner is almost always on a 3-3, 3-4, 3-5, 4-4 or 4-5 point.  Other plays that have been experimented with include 5-5, 6-3 and 6-4, all of which sacrifice territory for influence.
Of those plays, the classical 3-4 point (''[[komoku]]'') and more contemporary 4-4 point (''[[Hoshi (Go)|hoshi]]'') are the most used. The standard approaches are at 5-3 or 5-4 to the 3-4 point, and at 3-6/6-3 to the 4-4 point. The number of subsequent variations is then quite large (of the order of ten reasonable plays for the next one). Recently, some 3-3 invasion josekis became popular after it was used successfully by the [[AlphaGo|AlphaGo series]] of models, such as the [[:zh:飛刀定式|flying knife joseki]].<ref>{{Cite web |title=Flying knife joseki at Sensei's Library |url=https://senseis.xmp.net/?FlyingKnifeJoseki |access-date=2024-09-22 |website=senseis.xmp.net}}</ref>
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| style="text-align:center" | A Go game opening with two common ''jōseki'' in the upper-right and lower-left.
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Breaking away from a sequence to play elsewhere (''[[tenuki]]'') before the conventional endpoint of the ''jōseki'' is not uncommon in higher level play. There is no formal theory for follow-up plays after ''jōseki'', though numerous set sequences can be seen in professional play.
It is imperative that players should not play a ''jōseki'' merely from rote memorization but adapt according to the overall board situation. It is important to keep in mind that go is a game involving [[marginal analysis]] and ''jōseki'' are merely [[heuristics]] of sound play. Playing ''jōseki'' blindly will not improve one's game.{{fact|date=April 2014}}
== ''Jōseki'' in shogi ==
In [[shogi]], typically the [[Shogi opening|beginning of the games]] (序盤 ''joban'') consists of a number of relatively fixed series of moves for both players''.'' This standard sequence of moves or a '''jōseki''' (spelled 定跡, unlike in ''go'' where they are spelled {{nihongo2|定石}}) refers to especially recommended sequences of moves for a given [[Shogi opening|opening]] that lead to a balanced play for both sides. These sequences of moves are considered to be the best for a particular opening from the start of the game to the start of a full-scale battle, and are often recommended to amateur players to be able to master basic strategy.<ref>{{Cite book|last=Habu|first=Yoshiharu|url=https://www.worldcat.org/oclc/883614271|title=Habu yoshiharu no jōseki no kyōkasho|last2=羽生善治.|date=2014|publisher=Kawadeshobōshinsha|isbn=978-4-309-27511-6|location=Tōkyō|pages=3|language=ja|trans-title=[[Yoshiharu Habu]]'s Jōseki coursebook|oclc=883614271}}</ref> Jōsekis are typically developed by [[Professional shogi player|professional players]] as a result of their individual research and actual games.<ref>{{Cite book|last=Kitao|first=Madoka|url=https://www.worldcat.org/oclc/793802621|title=Joseki at a glance|last2=北尾まどか|date=2011|publisher=Nekomadosha|others=Tomohide Kawasaki, 川崎智秀.|isbn=978-4-905225-01-0|edition=Shohan|location=Tōkyō|oclc=793802621}}</ref> Jōsekis change continuously, some even becoming obsolete when they are reevaluated to no longer end up in a balanced play.
Examples of jōsekis in shogi include the [[Saginomiya joseki]], the [[Kimura joseki]], and the [[Yamada joseki]].
==See also==
* [[Go opening theory]]
* [[Fuseki]]
* [[Avalanche joseki]]
* [[Taisha joseki]]
* [[Shogi opening]]
== References ==
{{Reflist}}
==External links==
* [http://senseis.xmp.net/?Joseki Joseki sequences at Sensei's Library]
{{Go (game)}}
[[Category:Shogi theory]]
[[Category:Go joseki|*]]