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BeginnerExercise17

 

Beginner Exercise 17 Solution
   

KarlKnechtel: Ooo, some complexity here. Looking more like an actual game situation than tsumego usually do to me. ;)

[Diagram]
Diag.: Easy targets

Black can obviously capture the marked stones if it's his move. ;) Let's see what happens if he tries to go for the big kill. First, he will have to prevent white from connecting to the outside:


[Diagram]
Diag.: Trying for the big kill - divide and conquer

This is the way to do it - black forms a BambooJoint so that c and d are miai to keep his stones connected, while a and b are miai to cut - we can worry about them later. Other plays won't do it - black 1 at a,b or c will be answered by white 2 at d, letting white connect via capturing the marked stone, and black 1 at d is answered by white 2 at b, leaving 1 and a as miai to connect.


[Diagram]
Diag.: White responds...

Now, white takes advantage of sente to win the semeai at the bottom, using the techinque from an earlier problem. Otherwise, black 3 at a and it's all over for white. The 3-4 exchange is sente for black, because of the threat to connect to the stones inside, and reduces white's EyeSpace.

HolIgor: 3 is bad here.


[Diagram]
Diag.: Time for the capture

White captures because there's nothing else useful to do locally; and if she tenukis, black 7 at a forces the capture and leaves one fewer liberty.


[Diagram]
Diag.: Can black kill?

Black 7 appears necessary - with any other move, white 8 at 7 produces the requisite two eyes (three eyes, actually). Let's check white's responses:


[Diagram]
Diag.: White tries to make eyes

This dies in gote.


[Diagram]
Diag.: White tries to make eyes

Same with this, I'm pretty sure.


[Diagram]
Diag.: White tries to make eyes

No good.


[Diagram]
Diag.: White tries to make eyes

It looked promising, but fails.


[Diagram]
Diag.: White tries to make eyes

That's it. Even if the circled liberty had been filled, black can't atari with 9 because of damezumari. So black's grand plans are bound to fail, and he should just take the two stones on the side while he can (white doesn't get eyes on the bottom, but connects and escapes successfully). Note: If the marked stone had been black originally (so that white would capture it), then white would have to be careful to capture right away at move 6. Otherwise, the marked space is no longer a liberty; and black 9 (which is now playable; the damezumari is gone without the marked stone) is killing. What a hamete that would be - white doesn't appear to be threatened, so she assumes sente and tenukis; but it comes back to haunt her after she is forced to capture six stones and still can't make life or connect! (Or does white have other options without the marked white stone being in place? I'm not sure...)



Dieter: Karl, you're close in the diagram "white responds ...". As a shodan it took me a while before the rabbit bit the bamboo #:7 . Nice problem, unkx80.

"Close"? What did I miss? :/

unkx80: Thanks Dieter. =)

Hint: It is possible to almost fill the white group into a particular kind of big eye (nakade).

KarlKnechtel: Hmm... ok, how about this:

[Diagram]
Diag.: Don't bite!

Black can now play 3 because of not 'biting the bamboo'. It threatens to capture, so white captures...


[Diagram]
Diag.: Rabbity six

Black makes the nakade inside a "rabbity six" (so now I get all of Dieter's pun). a and b are miai to prevent an attempt by white to DivideTheSpace.

Mental note: For 'killing' tsumego, don't put a high priority on reducing eyespace if you're trying to cooperate with inside stones!





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