Gokyo Shumyo, Section 1, Problem 3 / Solution

Authors:

Table of contents Table of diagrams
Main line
2 and 3 are miai (i)
2 and 3 are miai (ii)
2 and 3 are miai (ii continued)
Variation
Wrong (i)
Wrong (ii)
White kills at 'a'
White kills at 'b'
White ignores threat of 'a'
White ignores threat at 'b'
Wrong (iii)
Variation
Variation (2 at 1-2 point)
First try
Suggestion
Main line
Variation 1
Variation 2
Variation 3
No sente


Solution

[Diagram]
Main line  

After B1, which makes an eye at the circled point, a and b are miai for life.

[Diagram]
2 and 3 are miai (i)  

After B3, Black has real eyes at the circled points.

[Diagram]
2 and 3 are miai (ii)  

It seems as if W2 creates a false eye, but the capture of three stones on the first line with B5 results in a real eye.

[Diagram]
2 and 3 are miai (ii continued)  

Even if White throws in at W6, Black lives with B7.


[Diagram]
Variation  

If White captures a Black stone with W2, B3 makes a second eye. Howver, if Black doesn't respond, White a kills the group.


Failure

[Diagram]
Wrong (i)  

B1 at the other 1-2 point is wrong. With W2, Black is dead. Even if Black is allowed two moves in a row, he can't live.


[Diagram]
Wrong (ii)  

When Black plays B1 here, White can choose between a and b to kill Black. Someone with an opinion which is the better ?

[Diagram]
White kills at 'a'  

We must look at the ko threats black has. Here black can make two eyes by playing both 'a' and 'b', so either of them can be used as a ko threat. However, this is the only threat black can have from this position.

[Diagram]
White kills at 'b'  

Here black will again live by having both 'a' and 'b', so they are both ko threats. Again, no more threats for black. So, are the moves equal?

[Diagram]
White ignores threat of 'a'  

Let's say the ko was crucial enough that white had to ignore this threat. Can white have ko threats of her own to kill black again, if another big ko appears in the game? W1 is the best she can do, threatening to make a ko for black's life at 'a'.

[Diagram]
White ignores threat at 'b'  

Here, however, white can make a threat to kill the black group without a ko (by filling at black+circle). 'a' is still playable, for the ko would be a hanami ko for white. Therefore, I feel that 'b' was slightly better than 'a', but the difference is really small. --Dansc

What is this diagram about? It isn't part of the immediately prior sequence. -- SGBailey


[Diagram]
Wrong (iii)  

Connecting with Black B1, as shown here, is also wrong. W2 and W4 leave a and b as miai for the kill.


Analysis by Members of Sensei's Library

[Diagram]
Variation  

Making the eye as large as possible, with B1 here, seems live, but it is not the solution from the book. After W2, B3 follows, and Black lives as shown.
Alternatively, if W3 would be followed by B2, White a, B7.
W7 is answered by B3.
W4, B7.
W5, B4.

[Diagram]
Variation (2 at 1-2 point)  

If Black 1 is a mistake, then it must be because White can next play at 2. If Black now plays 3, White 4 kills the entire black group. But ...

[Diagram]
First try  

... when Black throws in at 3, White fails.


The authors of the variations shown here, have not yet found the reason why B1 in the Main Line of *Solution* is preferred to B1 of *Analysis by Members of Sensei's Library*.

--DieterVerhofstadt

[Diagram]
Suggestion  

I received the following suggestion. White 2 is sente against Black 1. If Black doesn't answer ...

[Diagram]
Main line  

4 at 1. The result is ko.


Bill: Maybe this is the main line.

[Diagram]
Variation 1  

W5 takes ko.

Black lives with B4 and B6, sacrificing a few stones.

[Diagram]
Variation 2  

B4 fills ko.

To avoid that, maybe White should start with W1. Now B4 fills and W5 is sente. This is better for White than the next diagram.

[Diagram]
Variation 3  




[Diagram]
No sente  

In the Main Line solution , White's descent at W2 is not sente.


Back to Gokyo Shumyo Tsumego Series
Go to Problem 4


Gokyo Shumyo, Section 1, Problem 3 / Solution last edited by leothelion on July 8, 2014 - 21:07
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