Walkie Talkie Seven

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[Diagram]

Walkie Talkie Seven

This shape can be turned into a throw-in ko. White has two occasions to turn it into seki. The more outside liberties, the less likely the ko will be played (and thus the more likely White makes it seki in the end).

[Diagram]

Main line

The vital point of this shape obviously is W1. After W3, any move by Black other than a results in death in gote. It is no use for Black to throw in at a either, as it makes a ten thousand year ko.

If Black connects at a, his eyeshape is reduced to a pyramid four, and therefore Black is dead. Playing on either of the points b allows White to capture at a and this puts Black in atari. Unless Black is komaster with big ko threats, he is unlikely to want to play on either point b.

Letting White capture at a and connect at B1 turns this a position in a seki.




[Diagram]

Playing out the ko (Part 1)


(B1 and B7 = tenuki; W6 takes ko at W2, B9 takes ko at B2)

[Diagram]

Playing out the ko (Part 2)


(B13 and B15 = tenuki)


If Black plays elsewhere instead of starting the ten-thousand year ko, White can try to capture the corner by playing out the ko. However, White will need two more ko threats than Black, and Black will get to play four moves elsewhere in exchange for the corner (B1, B7, B13, and B15). If White doesn't have enough ko threats, an option is to back down by playing W8 at B3 in the first diagram to make a seki, but Black would still get to play three moves elsewhere (B1, B7, plus one more move elsewhere after White makes seki).

Hence, it would be difficult for White to win the ko without being komaster.



[Diagram]

Variation

Thus, when neither side has enough ko threats, White can also settle for seki.

[Diagram]

Variation at 2

This way the position becomes a direct ko, which is an inferior result for Black. White can finish the ko by filling at W2 - it would be a mistake to play one of the other inside liberties instead.



[Diagram]

Special case: If Black has 3 or more external liberties

Although the situation shown here is perhaps unlikely to occur in real games, it is of theoretical importance. If Black's group has three or more external liberties, White cannot kill anymore, as Black can set up an oshitsubushi as shown.


See also

Bulky seven in the corner


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