User:ZincBelief/SAT

Tactics
In Go, 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, not

limited to only part of the board, are referred to as strategy, and are covered in their

own section.

Capturing tactics
There are several tactical constructs aimed at capturing stones. 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.

A ladder. Black cannot escape unless the ladder connects to friendly stones further down the

board.

The most basic technique is the ladder. To

capture stones in a ladder, a player uses a constant series of capture threats &mdash;called

atari&mdash; to force the opponent into a zigzag pattern as shown in the diagram to the

right. Unless the pattern runs into friendly stones along the way, the stones in the ladder

cannot avoid capture. Experienced players will recognize the futility of continuing the

pattern and will play elsewhere. The presence of a ladder on the board does give a player

the option to play a stone in the path of the ladder, thereby threatening to rescue his

stones, forcing a response. Such a move is called a ladder breaker and may be a powerful

strategic move. In the diagram, Black has the option of playing a ladder breaker.

A net. The chain of three black stones cannot escape in any direction. Another technique to capture stones is the so-called net, 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 diagram to the left. It is generally 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.

A snapback. Although Black can capture the white stone by playing at the circled point,

White can then snap back by playing at 1 again. A third technique to capture stones is the snapback. In a snapback, one player allows a single stone to be captured, and then

immediately plays on the point formerly occupied by that stone; by so doing he captures a

larger group of his 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 will 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. Reading ahead consists of considering available moves to play, considering the

possible responses to each move, the subsequent possibilities after each of those responses,

etcetera. Some of the strongest players of the game can read up to 40 moves ahead even in

complicated positions.

As explained in the section on [[Go (board game)#Important_consequences|important

consequences]] of the basic rules, some formations of stones can never be captured and are

said to be alive, while other stones may be in the position where they cannot avoid

being captured and are said to be dead. Much of the practice material available to

students of the game comes in the form of life and death problems, also known as

tsumego. In such problems, players are challenged to find the

vital move sequence that will kill a group of the opponent or save a group of their own.

Tsumego are considered an excellent way to train a player's ability at reading

ahead, and are available for all skill levels, some posing a challenge

even to top players.

Ko fighting
In situations where the ko rule applies, prohibiting a player to capture to avoid

repetition, a ko fight may occur. If the player who is prohibited from

capture is of the opinion that the capture is important, for example because it prevents a

large group of stones from being captured, the player may play a ko threat. 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. His 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 he does not

think it important, or because there are no moves left that could function as a ''ko

threat, he has lost'' the ko, and his 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. He thereby wins 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 &mdash;points lost or gained&mdash;

of each of the remaining threats is.

Frequently, the winner of the ko fight does not connect the ko but instead captures one of

the chains which constituted his opponent's side of the ko. In some cases,

this leads to another ko fight at a neighboring location.

Strategy
[[Image:Noname 1.png|right|frame|Game 1 of the 2002 LG Cup final between Choe Myeong-hun

(White) and Lee Sedol (Black) at the end of the opening stage; White has developed a

great deal of potential territory, while Black has emphasized central influence.]]

Strategy deals with global influence, interaction between distant stones, with keeping the

whole board in mind during local fights and other issues that involve the overall game. It

is therefore possible to allow a tactical loss when it confers a strategic advantage.

Go is not easy to play well. With each new level (rank) comes a deeper appreciation for the

subtlety and nuances involved and for the insight of stronger players. The acquisition of

major concepts of the game comes slowly. Novices often start by randomly placing stones on

the board, as if it were a game of chance; they inevitably lose to experienced players who

know how to create effective formations. An understanding of how stones connect for greater

power develops, and then a few basic common opening sequences may be

understood. Learning the ways of life and death helps in a fundamental way to develop

one's strategic understanding of weak groups. It is necessary to play some thousands of

games before one can get close to one's ultimate potential Go skill. A player who both plays

aggressively and can handle adversity is said to display kiai or fighting spirit in

the game.

Familiarity with the board shows first the tactical importance of the edges, and then the

efficiency of developing in the corners first, then sides, then center. The more advanced

beginner understands that territory and influence are somewhat interchangeable—but there

needs to be a balance. This intricate struggle of power and control makes the game highly

dynamic.

Basic concepts
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 and usual

way is for the group to surround two eyes (separate empty areas), so that filling one eye

will not kill the group; as a result any such move is suicidal and the group cannot be

captured. The fundamental strategy of Go is to create groups with life while preventing

one's opponent from doing the same.
 * Mutual Life (seki): A situation in which neither player can play to a particular point

without then allowing the other player to play at another point to capture. The most common

example is that of adjacent groups that share two "eyes". If either player plays in one of

the eyes, they reduce their own group to a single eye, allowing their opponent to capture it

on the next move.
 * Death: The absence of life coupled with the inability to create it, resulting in the

eventual removal of a group.
 * Invasion: Setting up a new living position inside an area where the opponent has greater

influence, as a means of balancing territory.
 * Reduction: Placing a stone far enough into the opponent's area of influence to reduce the

amount of territory he/she will eventually get, but not so far in that it can be cut off

from friendly stones outside.
 * Sente: A play which forces one's opponent to respond (gote), such as

placing an opponent's group in atari (immediate danger of capture). A player who can

regularly play sente has the initiative, as in chess, and can control the flow of the

game.
 * Net gain: A player should always seek the move that will result in the best net advantage

to the player. Conversely, a player may pass his turn if he cannot find a move that results

in a benefit; a player is thus never forced to play when doing so would place him at a

disadvantage. This becomes important in the endgame, when groups are well-established,

uncontested points are few, and being forced to play may either simply be suicidal or may

"kill" a group (by playing into an eye or ending a seki situation).

The strategy involved can become very abstract and complex. High-level players spend years

improving their understanding of strategy, and a novice may play many hundreds of games

against opponents before being able to win regularly.

Opening strategy
In the opening of the game, players will usually play in the corners of the board first, as the presence of two edges make it easier for a player to surround territory and establish his stones. After the corners, focus moves to the sides, where there is still one edge to support a player's stones. Opening moves are generally on the third and fourth line from the edge, with occasional moves on the second and fifth lines. In general, stones on the third line offer stability and are good defensive moves, whereas stones on the fourth line influence more of the board and are good attacking moves. In the opening, players often play established sequences called joseki, which are locally balanced exchanges. However the joseki chosen should also produce a satisfactory result on a global scale. It is generally advisable to keep a balance between stability and influence. Which of these gets precedence is often a matter of individual taste.

Middlegame strategy
section needed

Endgame strategy
section needed

Musings
These two sections must be merged. The start of tactics is beautiful. Reading ahead could be improved I think. I think the srategy introduction is suspect. Net Gain seems unconvinving. Ko must be checked carefully. A discussion of opening theory should be complemented in some way by middle and end game strategies.