Four stones on the third line in the corner

   
[Diagram]

Four stones on the third line in the corner

This is the Four stones on the Third line in the Corner. Clearly, Black can play first to kill. This is unconditionally alive if White plays first.

[Diagram]

White first

This is usually the best path for White, making a and b miai for life. Later the cutting point at c may become a problem for Black.

[Diagram]

Small Life

This W1 is simpler, but gives only two points of territory and Black's outside is defect-free.

[Diagram]

Hane-Descend

Playing at W3 (hane-descend) is a mistake: Black can make ko:

[Diagram]

Hane-Descend - Ko

Black starts the ko by taking the vital point with B1.


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