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Two Space Notchers Not Fully Connected
    Keywords: Life & Death

Two Space Notchers (Not Fully Connected)

[Diagram]
Diag.: Black can live

So long as a is not occupied by White, Black can live (provided Black plays first). The vital point is at b.


[Diagram]
Diag.: Black can live (correct play)

The placement at 2 won't work. After Black 3, a and b are miai, so the black group has two eyes.


[Diagram]
Diag.: Black can live (correct play)

Black has to be careful in responding to the hane at 2. Only playing at 3 will live. Playing at a is wrong.


[Diagram]
Diag.: Black can live (wrong play)

Playing at 3 is wrong. White makes a placement tesuji at 4, causing an exchange at 5, followed by connecting at 6. Black faces a shortage of liberties - being unable to play at a - and dies because the eye on top cannot be formed.


[Diagram]
Diag.: Black can live (wrong play)

Black 1 is a very careless move. White 2 is a tesuji, followed by the atari at 4 which destroys an eye in sente, and then White 6 destroys another eye. Now Black is dead.


[Diagram]
Diag.: Black can live (wrong play)

Black 1 is also wrong. White plays a placement at 2, followed by cutting at 4 in sente (aiming to capture three black stones at a), before making the final killing move at 6.


[Diagram]
Diag.: Black can live (wrong play)

The sagari at 1 is incorrect as well. White can kill the group with a hane at 2 (aiming to capture two black stones at a), followed by a placement at 4. Black 5 attempts to divide the space to make two eyes, but the connection at 6 leaves Black with a shortage of liberties, and Black cannot play at b to defend the second eye.



[Diagram]
Diag.: Black is dead

The two marked white stones make it impossible for the black group to live, even though it has extra liberties outside. Try figuring it yourself, using the last three diagrams in the "Black can live" section as reference. Good luck!

DieterVerhofstadt: I refer to this particular shape in Tsumego From Games 4, so I'll work this out myself, although unkx80 left it as an exercise to the reader. I'll make it a separate page: the Flying Saucer Shape.



--unkx80



This is a copy of the living page "Two Space Notchers Not Fully Connected" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.