Gokyo Shumyo, Section 1, Problem 20b / Solution

Main line

Main line  

W1 is the only move. The only correct answer for Black is at B2. White's correct answer is at W3, and note that White must capture the black stone at W5, resulting in ten thousand year ko.


Variation at 2  

This dies easily.

Variation (ii) at 2  

Death in bulky five. If Black continues with atari at a, White simply connects at W4.

Variation (iii) at 2  

After W3, a and b are miai.

Variation (iv) at 2  

Resistance at B2 is useless here.

Variation (v) at 2  

The black group dies as well: a and b are miai.


Mistake at 3  

If White plays at W3 here, Black lives in seki: either he makes seki at a, or if White plays there, Black can capture her bent four in timely fashion.

Mistake at 1  

With the clamp at B4, Black lives.


If White plays at a to prevent a seki, then Black plays at b to form a bent four live group.


After B8 (oshitsubushi), White is short of liberties and cannot play at black+circle to form a bulky five, so Black lives.

Variation after the mistake  

White 4 here doesn't work... after B6, White is caught in a connect-and-die.

Another variation  

Same fate here if White chooses to take the ko at W5 instead.

Mistake upon mistake upon mistake


In Gokyo Shumyo, Section 1, Problem 20 black+circle was already a mistake. White's hane - as we now know - is another one and then B4 is yet another one.

W5 makes miai of a and b: b would enable White to almost fill Black's eye space with a bulky five and White a would make an eye inside Black's group. If Black rushes to capture White's stones, he's left with a farmer's hat space inside his group.

KarlKnechtel (~14k)

Can't Black also live by escaping with a monkey jump in this case?


No escape. --unkx80


Gokyo Shumyo, Section 1, Problem 20b / Solution last edited by CharlesMatthews on June 27, 2003 - 17:06
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