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Nakade
Path: LifeAndDeath   · Prev: BigEyes   · Next: AlmostFill
  Difficulty: Beginner   Keywords: Shape, Life & Death, Go term

A nakade is a play inside a big eye which prevents it becoming two (or more) eyes.

It is especially useful to identify positions where one move can decide whether there are one or more eyes in a certain space.


Basic nakade

[Diagram]
Diag.: Two points.

A two-point big eye is insufficient to live. In this position, white is dead.


[Diagram]
Diag.: Three points.

A three-point big eye (whether straight three or bent three) depends on sente. If black plays at 1, white is dead. If white plays there, she lives.


[Diagram]
Diag.: Four in a row.

Four spaces in a row, whether straight, or bent once (like an 'L') or twice (like a 'Z'), is enough to live. If black plays 1, white plays 2, and vice versa. (1 and 2 in the diagram are miai.)


[Diagram]
Diag.: Farmer's hat.

The shape here is known as the farmer's hat. Its life depends on sente. If white plays at 'a' she has three eyes, if black plays there white is reduced to a single eye and dies.


[Diagram]
Diag.: Block of 4.

A block of 4 on the other hand, is dead as it stands. Even if white plays first, black can kill her. It is not unsettled, and therefore no nakade is required.


[Diagram]
Diag.: Cross.

In this cross of size 5, black can kill white by playing at 1.


[Diagram]
Diag.: Bulky five.

This shape, nicknamed the 'bulky five' in English, is killed by the placement at 1.



Five-point shapes other than the cross and bulky five are alive even if black plays first.

[Diagram]
Diag.: A 5-point shape that is alive.

[Diagram]
Diag.: Another 5-point shape that is alive.


[Diagram]
Diag.: Rabbitty six.

Of the six-point big eyes, only this one can be killed. It is known as the 'rabbitty six' (it vaguely reminds one of a rabbit's head, the ears are at the top left) or 'nutcracker'. It is also known as the 'flower six' because the Japanese term for this shape is 'hana-roku'


[Diagram]
Diag.: Seven lives.

All eye shapes of seven points are alive. This shape is one that seems most likely to be killed, but after black 5 the position is seki. Actually, white could play tenuki after black 1 --- the situation is then already seki as it stands.



Other types of nakade

[Diagram]
Diag.: Cutting points.

Although the eye shapes that have not been discussed here are alive, there are still two situations in which that does not need to be the case. The first is the presence of cutting point(s) in the white shape. Normally, the 3x2 block is alive (3 and A are miai), but in this position, because of the two marked stones, black 1 is an atari, forcing white to answer at 2, after which black 3 kills the group.


[Diagram]
Diag.: Cutting point.

Another example of cutting point, more often than not coupled with shortage of liberties weaknesses. White 1 or a kills this seemingly alive bent four.


[Diagram]
Diag.: The corner.

The second possibility where problems can occur is in the corner. Because of the presence of the corner, white again dies despite her big 3x2 eye shape.

KarlKnechtel: See also TwoByThreeBox. (thanks unkx80!) The difference that the corner makes is that the point _a_ is not a liberty of the white group, where it would be if this formation were on the side. On the side, white 4 at _b_ makes two eyes; if white tenukis, black can make seki at _b_. In the corner, however, white is dead (as I appreciate fully now). If I've been paying attention, the distinction between BentFour and BentFourInTheCorner is basically the same.



Biggest known eye space for which there is a nakade

[Diagram]
Diag.: A problem from IgoHatsuyoron (Black to play).

The bigger the eye shape gets, the less likely it is that all surrounding stones can be killed. There is no known nakade for an eye shape bigger than 16 points. Here is [ext] the above problem as an applet.



See also


Authors include:



Path: LifeAndDeath   · Prev: BigEyes   · Next: AlmostFill
This is a copy of the living page "Nakade" at Sensei's Library.
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