Gokyo Shumyo, Section 1, Problem 52 / Solution

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 stones, to break through the stones or to make two eyes in the corner. With these weapons, Black has to find the proper order of moves to live.

Continuation  

After this , White suffers from shortage of liberties.

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

Continuation  

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

Variation at move 15  

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

Variation at move 14  

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

Variation at 8  

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

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

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

Variation at 6  

What if White at ignores atari and destroys the eye potential in the corner right away with here ?

Black makes the usual exchange for , then captures at . 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 seems arbitrary to me, so if you have thoughts on that one, please explain.

Failure at 1  

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

Failure (ii) at 1  

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

Failure (iii) at 1  

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

Variation  

Now a and b are miai.

Variation  

Incidentally, 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

Refutation  

Now Black cannot play A because of shortage of liberties. Any solutions?

IronChefSakai

Dieter: I think you are right and the solution appears to be ko

Outside complications  

hnishy Black may try this cut first....terribly difficult. He gets many local ko threats at least.