GokyoSeimyoVolume3Problem4/Attempts

[Diagram]

Vital point

W1 is the key move (although it fails). Examining where it succeeds and then the one refutation will lead to the solution.

[Diagram]

Ko

If black captures with B2, white starts a ko in the corner to capture three stones. Black cannot connect because of oiotoshi.

[Diagram]

Ko or double damezumari

This B2, preventing the throw-in, results in ko again. Although defending with B6 at W3 is no longer oiotoshi, white will then play W7 at a and it is double damezumari yet again.

[Diagram]

Double damezumari

If black plays B2 to prevent the ko, W3 results in double damezumari, and thus captures the black+circle stones.

[Diagram]

Throw-in

Preventing the ko with B2 doesn't work either. White throws in with W3, and after W5 it is double damezumari again.

[Diagram]

Refutation

However, after one black can play 2, and if white throws in at three black is safe after 4. Therefore..

[Diagram]

Correct sequence

White must make the throw in of 1 first, then play the vital point 3. Then no refutation is available.


This is a copy of the living page "GokyoSeimyoVolume3Problem4/Attempts" at Sensei's Library.
(OC) 2011 the Authors, published under the OpenContent License V1.0.
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