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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 an eye space 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
A two-point eyespace is insufficient to live. In this position, White is dead.
A three-point eyespace (whether straight three or bent three) depends on sente. If Black plays at 1, White is dead. If White plays there, she lives.
Four spaces in a row, whether straight, or bent once (like an 'L') or twice (like a 'Z' - twisted four), are enough to live. If Black plays 1, White plays 2, and vice versa. (So 1 and 2 in the diagram are miai.)
The shape here is known as the farmer's hat eyespace. 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.
A 2x2 block of four or squared four 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.
In this cross of size 5, Black can kill White by playing at 1.
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.
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
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
Although the eye shapes that have not been discussed here are alive, there are still two circumstances 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 rectangular six are 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.
Another example of a cutting point, more often than not coupled with shortage of liberties weaknesses. White 1 or a kills this seemingly alive bent four.
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 rectangular six in the corner. (Thanks unkx80!) The difference that the corner makes is that the point a is not a liberty of the white group, while it would be if this formation were on the side. On the side, White 4 at b makes two eyes; if White plays tenuki, 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 bent four and bent four in the corner is basically the same. Biggest known eye space for which there is a nakade See also Authors include: Path: LifeAndDeath · Prev: BigEyes · Next: AlmostFill This is a copy of the living page "Nakade" at Sensei's Library. (C) the Authors, published under the OpenContent License V1.0. |