Gokyo Shumyo, Section 1, Problem 52 / Solution

This is a really tough tsumego problem with a main line of 17 moves.

[Diagram]
Solution  

The challenge is to make an eye at the marked point, and still have time to make one in the corner. This is no easy task, because Black needs two moves to turn the marked point into a real eye; and a white move at a destroys any eye potential in the corner.



On the other hand, Black can threaten to capture the white+circle stones, to break through the white+square stones or to make two eyes in the corner. With these weapons, Black has to find the proper order of moves to live.

[Diagram]
Main line  
[Diagram]
Continuation  

After this B7, White suffers from shortage of liberties.

That is, Black can play as in the following diagram:

[Diagram]
Continuation  

White captures black+circle, but Black plays B2 and White can't connect at a or she loses five stones.


Now for some variations, backtracking from Black 17 to W1.


[Diagram]
Variation at move 15  

In response to white+circle (White 14) it is tempting to capture at B1, but White connects at W2 and leaves Black with two false eyes in the corner.


[Diagram]
Variation at move 14  

If White 14 is at W1 in this diagram, then Black plays B2 (can also be at a). After W3 and B4, White can't play at a, again because of shortage of liberties.


[Diagram]
Variation at 8  

After B7 (black+circle), the natural white response seems to be W1 here. In any case, it is the vital point.



But W1 is trapped already, and Black has time to make his second eye with B2 and B4.

Of course, if White prevents that second eye, Black makes two eyes in the corner, playing B1 himself.


[Diagram]
Variation at 6  

What if White at W6 ignores black+circle atari and destroys the eye potential in the corner right away with W1 here ?

Black makes the usual exchange B2 for W3, then captures at B4. This makes miai of a and b. the play at a clearly makes a second eye, and b in its turn makes miai of c and d.

As a sidenote, the timing of the forcing move at B2 seems arbitrary to me, so if you have thoughts on that one, please explain.


The whole meaning of B1 and B3 in the main line is to get B5 in place in sente. This stone serves amongst other things to prevent a connection underneath, as demonstrated in the "variation at 8".

[Diagram]
Failure at 1  

If Black immediately plays B1, White defends at W2, in the process destroying the eye potential there. Now Black has to make two eyes in the corner: which he can't do.


[Diagram]
Failure (ii) at 1  

B1 is vulgar. It destroys the possibilities and White defends at W2 with good aji. The move at B3 is still forcing, but now Black has run out of resources. White strikes at the vital point at W6 and makes miai of a and b.


[Diagram]
Failure (iii) at 1  

Now how about seeking life in the corner immediately? W2 destroys the eye above and even after B3, Black doesn't have two eyes in the corner.

[Diagram]
Variation  

Now a and b are miai.


[Diagram]
Variation  

Incidentally, B1 seems to work too: if a, then b makes an eye in sente. If tenuki from the corner then also life ? (To be continued.)

xela: I'm not convinced. Rather than clutter this page, let's call it Gokyo Shumyo, Section 1, Problem 52b


DieterVerhofstadt


Back to Kanazawa Tesuji Series
Go to Problem 53


Gokyo Shumyo, Section 1, Problem 52 / Solution last edited by xela on November 8, 2008 - 02:19
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