Gokyo Shumyo, Section 1, Problem 11 / Solution

Main line: Hashimoto Utaro 9p
Variations: Bill Spight, Dieter Verhofstadt 1k


Black to live  

The 1-2 point prevails over the 2-2 point again.

Black to live  

There is no way White can attack Black. The distance between B1 and black+circle is wide enough for him to make a second eye (the circled point).

Alternative life  

B1 here also lives.

Bill Spight: It loses almost 3 points by comparison to the correct play. White has the following sente sequences.

White sente  

W1 - B2 is a two-point sente play. W5 - B6 is 1 2/3 points in sente.

If Black omits B6, White kills:

White kills  



If Black carelessly plays at the 2-2 point, White takes the vital point with W2 and sets up an approach ko. Black can't block at a because of shortage of liberties. So he has to fight the ko at W2. After White recaptures the ko ...

Wrong (cont.)  

... she connects at W1, putting the four black stones in atari. Black takes the ko with B2 putting three white stones in atari; White connects at W3, and Black makes an eye with B4. Now White takes the ko.

So, White has to play an extra move, and if Black loses the corner, he will have played twice elsewhere in return.

Anyway, living unconditionally is much better for Black.

Wrong (ii)  

Enlarging the eyespace with B1 is dubious. After W2, Black has to defend his cutting point with B3. Further enlarging the eyespace with B5 forces W6 and now White can either play atari at a in the future, or if Black plays there, almost fill Black with a farmer's hat by playing at b.

Anonymous: Isn't Black at a death in gote? W has made it impossible to DivideTheSpace already.

unkx80: Yes. But "almost fill" does not mean that you must play there immediately.

Wrong (ii) (cont)  

Fancy play at B3 doesn't help much. After W4 on the 2-1 point, White can answer B5 with W6, preventing any escape. Black has only one eye. Now B7 and W8 are miai points.

Wrong (ii) (cont)  

Black does better to try to run with B3, eliciting W4. Now B5 sets up a ko.

Wrong (iii)  

B1 leads to a throw-in ko.


Gokyo Shumyo, Section 1, Problem 11 / Solution last edited by hnishy on January 12, 2023 - 07:27
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