Editing Go (game) (section)

== Tactics ==
{{Main|Go strategy and tactics}}

''Tactics'' deal with immediate fighting between stones, capturing and saving stones, life, death and other issues localized to a specific part of the board. Larger issues which encompass the territory of the entire board and planning stone-group connections are referred to as ''Strategy'' and are covered in the ''Strategy'' section above.

=== Capturing tactics ===
There are several tactical constructs aimed at capturing stones.{{sfn|Kim|Jeong|1997|pp=80–98}} These are among the first things a player learns after understanding the rules. Recognizing the possibility that stones can be captured using these techniques is an important step forward.
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{{Goban 9x9
| ul|  u|  u|  u|  u|  u|  u|  u|  u
|  l|   |  w|   |   |   |   |   |
|  l|  w|  b|  w|   |   |   |   |
|  l|  w| b1| b3| w4|   |   |   |
|  l|   | w2| b5| b7| w8|   |   |
|  l|   |   | w6| b9|   |   |   |
|  l|   |   |   | 10|   |   |   |
|  l|   |   |   |   |   |   |   |
|  l|   |   |   |   |   |   |   |   |22}}

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'''A ladder.''' Black cannot escape unless the ladder connects to black stones further down the board that will intercept with the ladder or if one of white's pieces has only one liberty.
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The most basic technique is the ''ladder''.{{sfn|Kim|Jeong|1997|pp=88–90}} This is also sometimes called a "running attack", since it unfolds as one player trying to outrun the other's attack. To capture stones in a ladder, a player uses a constant series of capture threats (atari), giving the opponent only one place to place his stone to keep his group alive. This forces the opponent to move into a zigzag pattern (surrounding the ladder on the outside) as shown in the adjacent diagram to keep the attack coming. Unless the pattern runs into friendly stones along the way, the stones in the ladder cannot avoid capture. However, if the ladder can run into other black stones, thus saving them, then experienced players recognize the futility of continuing the attack. These stones can also be saved if a suitably strong threat can be forced elsewhere on the board, so that two Black stones can be placed here to save the group.

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{{Goban 9x9
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|  l|  b|  w| bT|  w|   |   |   |
|  l|   |  w| bT|  c|   |   |   |
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|  l|   |  w|  c| w1|   |   |   |
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'''A net.''' The chain of three marked Black stones cannot escape in any direction, since each Black stone attempting to extend the chain outward (on the red circles) can be easily blocked by one White stone.
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Another technique to capture stones is the so-called ''net'',{{sfn|Kim|Jeong|1997|pp=91–92}} also known by its Japanese name, ''geta''. This refers to a move that loosely surrounds some stones, preventing their escape in all directions. An example is given in the adjacent diagram. It is often better to capture stones in a net than in a ladder, because a net does not depend on the condition that there are no opposing stones in the way, nor does it allow the opponent to play a strategic ladder breaker. However, the ladder only requires one turn to kill all the opponent's stones, whereas a net requires more turns to do the same.

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|  l|   |  b|  w|  w|   |   |   |
|  l|   |  w|  b|  c|  w|   |   |
|  l|   |  w|  b| w1|  b|  b|   |
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'''A snapback.''' Although Black can capture the white stone by playing at the circled point, the resulting shape for Black has only one liberty (at 1), thus White can then capture the three black stones by playing at '''1''' again (''snapback'').
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A third technique to capture stones is the ''snapback''.{{sfn|Kim|Jeong|1997|pp=93–94}} In a snapback, one player allows a single stone to be captured, then immediately plays on the point formerly occupied by that stone; by so doing, the player captures a larger group of their opponent's stones, in effect ''snapping back'' at those stones. An example can be seen on the right. As with the ladder, an experienced player does not play out such a sequence, recognizing the futility of capturing only to be captured back immediately.

=== Reading ahead ===
One of the most important skills required for strong tactical play is the ability to read ahead.{{sfn|Davies|1995|p=5}} Reading ahead includes considering available moves to play, the possible responses to each move, and the subsequent possibilities after each of those responses. Some of the strongest players of the game can read up to 40 moves ahead even in complicated positions.<ref name=TreasureChest>{{citation | chapter = Memories of Kitani | title = The Treasure Chest Enigma | last = Nakayama | first = Noriyuki | publisher = Slate & Shell | year = 1984 | isbn = 978-1-932001-27-3 | pages =16–19}}</ref>

As explained in the scoring rules, some stone formations can never be captured and are said to be alive, while other stones may be in a position where they cannot avoid being captured and are said to be dead. Much of the practice material available to players of the game comes in the form of life and death problems, also known as [[tsumego]].<ref name=Tsumego>{{Citation | url = http://www.yomiuri.co.jp/dy/columns/0001/305.htm | last = van Zeijst | first = Rob | publisher = [[Yomiuri Shimbun]] | title = Whenever a player asks a top professional&nbsp;... | access-date = 2008-06-09 | archive-date = 2008-05-11 | archive-url = https://web.archive.org/web/20080511122600/http://www.yomiuri.co.jp/dy/columns/0001/305.htm | url-status = dead}}</ref> In such problems, players are challenged to find the vital move sequence that kills a group of the opponent or saves a group of their own. Tsumego are considered an excellent way to train a player's ability at reading ahead,<ref name=Tsumego /> and are available for all skill levels, some posing a challenge even to top players.

=== Ko fighting ===
[[File:Gokof.png|thumb|A simplified ko fight on a 9×9 board. The ko is at the point marked with a square—Black has "taken the ko" first. The ko fight determines the life of the A and B groups—only one survives and the other is captured. White may play C as a ko threat, and Black properly answers at D. White can then take the ko by playing at the square-marked point (capturing the one black stone). E is a possible ko threat for Black.]]

In situations when the [[Ko rule]] applies, a ko fight may occur.{{sfn|Kim|Jeong|1997|pp=144–147}} If the player who is prohibited from capture is of the opinion that the capture is important because it prevents a large group of stones from being captured for instance, the player may play a ''ko threat''.{{sfn|Kim|Jeong|1997|pp=144–147}} This is a move elsewhere on the board that threatens to make a large profit if the opponent does not respond. If the opponent does respond to the ko threat, the situation on the board has changed, and the prohibition on capturing the ko no longer applies. Thus the player who made the ko threat may now recapture the ko. Their opponent is then in the same situation and can either play a ko threat as well or concede the ko by simply playing elsewhere. If a player concedes the ko, either because they do not think it important or because there are no moves left that could function as a ko threat, they have ''lost'' the ko, and their opponent may connect the ko.

Instead of responding to a ko threat, a player may also choose to ''ignore'' the threat and connect the ko.{{sfn|Kim|Jeong|1997|pp=144–147}} They thereby win the ko, but at a cost. The choice of when to respond to a threat and when to ignore it is a subtle one, which requires a player to consider many factors, including how much is gained by connecting, how much is lost by not responding, how many possible ko threats both players have remaining, what the optimal order of playing them is, and what the ''size''—points lost or gained—of each of the remaining threats is.<ref name="Tavernier">{{cite journal
 | url = https://www.britgo.org/files/bgj/bgj110.pdf
 | title = Analyzing Ko Struggles Theoretically
 | first = Karel
 | last = Tavernier
 | date = Spring 1998
 | access-date = 8 October 2013
 | journal = British Go Journal
 | issue = 110
 | page = 11
 | archive-url = https://web.archive.org/web/20150131052153/https://www.britgo.org/files/bgj/bgj110.pdf
 | archive-date = 31 January 2015
 | url-status = live
}}</ref>

Frequently, the winner of the ko fight does not connect the ko but instead captures one of the chains that constituted their opponent's side of the ko.{{sfn|Kim|Jeong|1997|pp=144–147}} In some cases, this leads to another ko fight at a neighboring location.