Gokyo Seimyo Volume 3 Problem 13 / Attempts

[Diagram]

Apperent vital point?

[Diagram]

Refutation

[Diagram]

Refutation? or big ko?

[Diagram]

Necessary forcing move

White should force with 1 first. Black must choose a, b, or c to avoid immediately sacrificing the two stones in the corner.

[Diagram]

Black loses 2 stones

After the sequence to 4 black is short of liberties, and must give up at least two stones in the corner. Black does get sente here, and this is the best he can do.

[Diagram]

Black loses 2 stones

Normally this ko will be too serious for black to fight. Move 1 at 5 will lead to the same ko.

[Diagram]

Final result

[Diagram]

This result is 3 points better, but it is gote, and sente will usually be worth more.


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